Onevariable linear equations
More fancy equations for beginners
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How to solve an equation with variables on both sides (20  7y = 6y  6)
Sal solves the equation 20  7y = 6y  6.
Discussion and questions for this video
 Solve for y and check your solution.
 20 minus 7y is equal to 6y minus 6.
 So, what I really wanna just do is isolate all of the y's on one side of this
 equation, and then if there's some coefficient in front
 of it, I can divide both sides by that coefficient.
 And I could isolate the y on either the
 left side or the right side of the equation.
 And actually, let me do it both ways.
 So first, let's, it, it'll looks like it'll be a little bit simpler if I
 isolate it on the right hand side, and I'll show you that in a second.
 So if I want to put all of the y's on the right hand
 side, how could I get rid of the y's on the left hand side?
 Well I have a neg, I have a minus 7y, or you could
 use the negative 7y, and can add 7y to both sides of this equation.
 So I'm just adding 7y to both sides.
 Then the left hand side of the equation we have have 20 minus 7y plus 7y.
 Those are gonna cancel out, you're gonna be just left with 20.
 And on the right hand side of the equation
 you're gonna have 6y plus 7y, which is 13y.
 And then you have your minus six.
 And, I want only y's or, or multiples of y's on the right hand side of
 the equation, so I need to get rid of this, this, this minus six over here.
 So let's add six to both sides of this equation.
 Let's add six.
 And then, on the, on the right hand side a 13y minus 6 plus 6, that's just 13y.
 Got rid of the minus six.
 And I have 20 plus 6, so that is 26.
 So I get 26 is equal to 13y.
 I've isolated the y on the righthand side, although it's being multiplied by 13.
 So if I just want a y on the righthand side.
 Or a one y on the right hand side, I can divide both sides by 13.
 Or the equivalent statement would be to multiply both sides by 1 over 13.
 Same thing.
 So, let's divide both sides of this equation by 13.
 On the right hand side 13 times y divided by 13.
 Well that's just gonna be y.
 So this is just y, and then 26 divided by 13 that is 2.
 So our solution that we got is y is equal to two.
 Now I want to take a step back, why did I say it would be a little
 bit easier to add to, to put the y's on the right hand side of the equation.
 Well because that way I've got a, a positive coefficient on, in terms of y.
 I got 13y.
 If I had subtracted 6y from both sides I would have got a negative
 13 on the left hand side, which would have been a legitimate thing to do.
 Let me just show you what I'm talking about.
 So I could have done the problem this way.
 20, do that in a different color, I could have said 20,
 let me just rewrite 20 minus 7y is equal to 6y minus 6.
 Now let me just subtract 6y from both sides.
 So minus 6y or negative 6y, from both sides.
 The left hand side over here, is 20 minus 13y.
 The right hand side, I got rid of that 6y.
 I just have the minus six here, it's just a negative six now.
 And now I can subtract 20 from both sides, to isolate the y's of the left hand side.
 So I am subtracting 20 from both sides.
 I'm doing that to get rid of this 20.
 And so on the left hand side I have a negative 13y and
 on the right hand side I have a negative, I have a negative 26.
 Now I wanna divide both sides of this equation by negative 13.
 So I wanna divide both sides of this equation by negative 13 and what do I get?
 Negative 13 times something divided by negative 13 is just that something.
 I just get a y and then negative 26 divided by negative 13 is 2.
 So I did it two different ways.
 Over here I isolated the y's on the left hand
 side, over here I did it on the right hand side.
 I picked the right hand side first so that everything stays
 positive but this is an equally valid way to do it.
 Now the last thing I want to do is just make sure that we got the right answer.
 We, we should probably feel pretty comfortable.
 We got the same answer doing it
 two different ways, but let's actually check it.
 Let's put y equals 2 back into the
 equation and verify that we get the equality.
 So we have 20 minus 7, y is 2, so 7 times 2 should be equal to 6 times 2.
 6 times 2 minus 6.
 So 20, this should be 20 minus 14,
 we're gonna want to do multiplication first, order of
 operations, so this is 20 minus 14 should be equal to 6 times 2 is 12 minus 6.
 20 minus 14 is 6, 12 minus 6 is 6, 6 is indeed equal to 6 so it all checks out.
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?

Have something that's not a question about this content? 
This discussion area is not meant for answering homework questions.
Does anyone know why he divides by 13 in the end
It is because he wants to find the value of 1y, not 13y.
Hey is trying to find what "y" is. its like a onetwo step equations except with more steps.
because he wants to find the value of 1y not 13y.
because 13 is a factor of 26 and 13 times 2 = 26
He is trying to get y by itself otherwise known as isolating the variable
he wants to find the value of 1y, not 13y. same as zoelvtt and knoreen09.
he divides by 13, because he only wants Y
because 207=13 and 7+6=13
He needed to just have Y by itself in order to see what it was equal to.
he's doing it coz he wants to find 1y not 13y's. same as zoelvtt said.
You need to isolate the variable
He divides by 13 in the end so he can get the value of y not 13 y!
i be sayin' dat da 13y be devided inta da 4
I dont get what your saying.
this is durifific
What if there are more than 1 "y" like 3 + 3y + 5y = 4  2y + 3y? Would you combine the y's?
you combine the y's to make the equation easier to work with, and so you can reduce messing up, and it takes less steps. does this help?
Just add the numbers together and add y at the end you can do this because all the numbers end with y if the question was
3y+5y+7 you add 3y and 5y together so you get 8y+7
3y+5y+7 you add 3y and 5y together so you get 8y+7
Yes, you would. Your little example is 8y+3=y+4, which simplifies to y=1/7.
Or you can just ask somebioyd
Yes. Yes you would.
yes.....because they are like terms
that means that they have a variable with the same power
just like 2+3+4=5+1+3
it adds up to 9=9
even though there's a y, the principle is the same
that means that they have a variable with the same power
just like 2+3+4=5+1+3
it adds up to 9=9
even though there's a y, the principle is the same
just combine the like terms ( the y's) to make it easier to work with
to make the equation simpler so you get 3+8y=45y
to make the equation simpler
so you get 3+8y=45y
so you get 3+8y=45y
What is a coofichant?
A coefficient is the number in front of a variable that tells how much of the variable is contained in the problem. For example, in the expression 2x, two is the coefficient. There are two x's, which can also be represented by x+x.
A coefficient is a number in front of a variable, like y, that tells you that if you have a number "y", 5y is 5 times the number y.
co efficient is just the number by which a variable is multiplied.
like 4x the co efficient (that which x is multiplied) is 4 !
hope this helps :D
like 4x the co efficient (that which x is multiplied) is 4 !
hope this helps :D
because when i did it it still came out with the right answer either way!!
Does it matter if you do any variable first??
yes you can combine the ys
How come he divides by 13 in the end?
He divides both sides by 13 to come up with only one y on the left side. 13y = 26 is not the full answer that we need, we are looking to find what the value of only 1 (one) y is and that is why we need to divide both sides by 13.
You can also multiply both sides by 1\13 (multiplicative inverse of 13) and you will get the same answer !
Divide both sides by 13:
13y = 26
13y/13 = 26/13
y=2
or multiply both sides by 1\13:
13y = 26
1\13 * 13y = 26 * 1\13
y=2
You can also multiply both sides by 1\13 (multiplicative inverse of 13) and you will get the same answer !
Divide both sides by 13:
13y = 26
13y/13 = 26/13
y=2
or multiply both sides by 1\13:
13y = 26
1\13 * 13y = 26 * 1\13
y=2
homechoolitshunk your name sucks because it is unfair that you think of homeschoolers that way............it is like being racist.
So you can be left with just y. If you have 13y=26, you cannot leave it because it needs to be simplified. If you divide y by 13, you can be left with just y, so you also need to divide 26 by 13. Therefore, y=2 Hope this helps ;)
so the 13y is just 13 so now alll he has to do is divide 26 by 13
you need to get the variable by itself
Vote up if you think sal is 100 times better than a normal teacher!!!!
and homeschoolers ROCK!!!
this is for the homeschoolshunk post... your name is terrible because you are olbviously mad you are homeschooled. :)
because 13y is the same as 13 times y, and so to get y just divide by thirteen. and of course you can't forget to do the other side to.
because 13 is the coefficient
maybe he thot that it woudle be easyer or fun to divide by 13
technically 13y does not equal 13. the reason for this is because 13y could be 13 yogurts and the regular 13 is not 13 yogurts. 13 is just a number it does not classify anything at all unlike 13y. sorry hope you understand the technicality of this... :)
They are both the same thing.
B/C you have to isolate the Y.
Because you need to leave the y by itself.
To isolate the variable :P
look at you all so smart! ;p
how do you know this all math? you are awsome and whats your name
His name is Sal Khan.
you just got flagged a.s.r.s better watch your language next time
Salman Khan
His name is Salman Khan, and some ppl are just born amazing...Einsten, Edison, etc...
his name is Sal
A.S.R.S WATCH IT MISTER DONT FORGET I CAN REPORT YOU SAL IS MY BRO!
Salman Khan, and by the way, if you hadn't guessed already, I think its awesome! (and famous at least in my family!)
i know how, but i seem to keep forgeting how
his name is Sal and he knows it because he's awesome :)
Salman Khan, KHANacademy? Duh!
dude watch your freaking langauge A.S.R.S.!
Does anyone know why he divides by 13 in the end
So then he can get the y value by its self and your answer ends up being y=2
No do not know.
I thought the anser equaled 3 because when you add on one side you hve to to to the other side
Because since he is multiplying by Y technaclliy, he does the oppisite of multiplying and divides by 26.
Dividing by 13 makes it easier, if he divided by 26 it would have been a decimal answer.
The reason he divides by 13 in the end is so he can get the value of y not 13 y. That is just simplifying it all of the way.
is there any other way to solve this equation?
It's more confusing until you get used to it, but some write in the operations (say, adding 2x or dividing by 3) inside the existing line's equation. This becomes much more common at college level where no one wants to write 50 lines for simplifying to 10a 3b + 7c + 2x + 4y  5z = 8 from where there's likely a bunch of variables on a side you don't want them to be. You just do several subtractions/additions at once and then divide the entire equation by the coefficient. It gets really burdensome when you're dealing with a dozen terms or more to do it one term at a time! If you want an actual example of doing multiple terms at once, I can probably find one for you or you can just look up precalc/trigonometry videos to see it in action.
Can't be 100% sure about existing of other ways to solve it, but grouping and factoring method Sal uses here is the most simple and efficient for such linear equation.
We could "move" our variables to the left hand side and, which would result 13y= 26, than divide both side by 13, but that's essentially the same way.
We could "move" our variables to the left hand side and, which would result 13y= 26, than divide both side by 13, but that's essentially the same way.
How do you know or decide which side of the equation to put the variables on?
There is no difference whatsoever. Right or left works. Depends on what you are comfortable with. Generally you will move it to the left, unlike Sal did here, but either way's fine. Like Caroline said, you read left to right. Just do what you are comfortable with. Both sides will come out the same.
It depends on what you are comfortable with. I usually put the variables on the left side, just like reading a book: you read from the left to the right. But when you are solving, sometimes you will have negative variables, so I usually add them to both sides, and get the positive variables on the other side and no variables on the previous side. Overall, just do what you normally feel is right. It will not change your answer if you put it on either side. hope this helps! :)
How do you solve this equation e/5  6 = 9
Anthony is correct in his answer, but let me show you how he got it.
You would approach the problem as follows: First, add 6 to both sides. The equation now reads e/5 = 3. Next, multiply both sides by 5, which leaves us with e = 15.
I hope this was helpful!
You would approach the problem as follows: First, add 6 to both sides. The equation now reads e/5 = 3. Next, multiply both sides by 5, which leaves us with e = 15.
I hope this was helpful!
The value of e in that equation is 15.
were do i go to practice this?
It is on the top bar of this website or just go to this link www.khanacademy.org/exercisedashboard
Look up on google
look it up in google.
yo go to the exercise dash board and type in multistep equations.
Some videos have a green excersise button above them. This one doesn't have one.
how do you this problem? y11=4/5(x13)
i dont get how you come up with 2 y insted of 1 y
I have a question that needs solving what do i do for
7  3z = 8 + 2z
7  3z = 8 + 2z
When I look at an equation like this, I like to keep the variable positive, so when I see 3z on one side and 2z on the other, I want the z to have a positive coefficient in front of the variable. To do that, I'm going to *add* 3z on both sides of the equation because if we subtracted 2z from both sides, the coefficient on the left side of the equation would be 5z. So, we add 3z on the both and you should get 7 = 8 + 5z.
We want to get z on one side of the equation, so to do that we'll have to work with the order of operations. Instead of starting with multiplication like you would expect, we are going to start at the addition/subtraction part of the order of operations because we are trying to get a variable by itself. We start by *subtracting* 8 on both sides of the equation and we should come up with 15 = 5z.
Now the problem looks pretty straight forward. Just divide 5 on both sides to get z by itself. The answer is 3 = z.
Hope this helped.
We want to get z on one side of the equation, so to do that we'll have to work with the order of operations. Instead of starting with multiplication like you would expect, we are going to start at the addition/subtraction part of the order of operations because we are trying to get a variable by itself. We start by *subtracting* 8 on both sides of the equation and we should come up with 15 = 5z.
Now the problem looks pretty straight forward. Just divide 5 on both sides to get z by itself. The answer is 3 = z.
Hope this helped.
Hope it Helps
Do the variables have to go on the left side ?
No, variables can go on either side. Left side is preferred though, because you read left to right. Right or left, it doesn't matter, both will come out with the same answer.
No, the variables can go on either side, left or right, but most people like to put it on the left side because it is "easier" to solve for the variable that way.
how do i solve 24=6(x3)
Well, to get you started, you would use the distributive property and get:
24=6x18
Hope this will help!
Imagineer ;)
24=6x18
Hope this will help!
Imagineer ;)
24=6(x3)
24=6x18 (distributive property)
24=6x18 (isolating the variable)
+18 +18
42=6x (to get (x) by itself)
/6 /6
x=7
24=6x18 (distributive property)
24=6x18 (isolating the variable)
+18 +18
42=6x (to get (x) by itself)
/6 /6
x=7
Can't you not do the subtraction and just move numbers with or without variables to the other side? Would that not get you the answer as well? For example, with
20  7y = 6y6, you could move 7y to the other side so that it becomes positive and equals 6y + 7y which also equals 13y. And then you could move 6 to the other side so it also becomes positive and adds up to 26. Then 26 = 13y is simplifiable into 2 = y. Is that not possible as well?
20  7y = 6y6, you could move 7y to the other side so that it becomes positive and equals 6y + 7y which also equals 13y. And then you could move 6 to the other side so it also becomes positive and adds up to 26. Then 26 = 13y is simplifiable into 2 = y. Is that not possible as well?
Abhijeet,
Yes, you can definitely "just move it to the other side and change the sign".
But when you do, what you are really doing is subtracting (or adding) the same thing to both sides, and then using the identity property of addition to make the expression subtracted from itself to become zero and disappear.
It is important to understand the concept of adding or subtracting the same thing from each side which allows the expressions on each side remain equal.
Once you fully comprehend the concept of doing the same thing to each side, you can then skip the intermediate steps and it will look like you just move the expression to the other side while reversing the sign.
Yes, you can definitely "just move it to the other side and change the sign".
But when you do, what you are really doing is subtracting (or adding) the same thing to both sides, and then using the identity property of addition to make the expression subtracted from itself to become zero and disappear.
It is important to understand the concept of adding or subtracting the same thing from each side which allows the expressions on each side remain equal.
Once you fully comprehend the concept of doing the same thing to each side, you can then skip the intermediate steps and it will look like you just move the expression to the other side while reversing the sign.
At 0:22 do you have to add 7y or subtract 6y?
Can't you add 6 to both sides?
Can't you add 6 to both sides?
Yes, you can do either, add 7y to both sides or subtract 6y from both sides, it doesn't matter. If you subtract 6y instead of adding 7y you will get :
207y=6y6
subtract 6y from both
2013y=6
subtract 20 from both sides.
13y=26
divide both sides by 13
y=2
You would not add 6 to both sides, 6y is positive, you do the opposite operation when you move a number to the other side of the equation, you would subtract 6y from both sides.
207y=6y6
subtract 6y from both
2013y=6
subtract 20 from both sides.
13y=26
divide both sides by 13
y=2
You would not add 6 to both sides, 6y is positive, you do the opposite operation when you move a number to the other side of the equation, you would subtract 6y from both sides.
#EatDonuts66=0
how to solve a variable with decimal?
Same way how u solve that. :)
Who is Alyana F.???
how should i know that
iiiiiiiii dont knooooooooooooow :)
Is'nt there a certain problem where the answer is unknown?
Yes, sometimes there is no answer. But only if the equation has variables on both sides.
There are answers that are undefined, like 0 to the power of 0 (it isn't an equation, though).
At 3:23, couldn't have Sal divided/multiplied by 1 before dividing by 13? That way, it would all be positive without dividing by negatives, which is hard for some (not including me) to understand, therefore making this lesson easier?
You could do that  but because meany do find dividing by negatives troublesome, Sal did it this way on purpose. In the end, dividing 2 negatives is a skill that must me mastered as soon as possible, or it will be the cause of numerous errors later on.
What is a coefficient?
A coefficient is the constant that is multiplied by a variable.
For example, in `2x + 7` the coefficient of x is 2
And in `x/5` the coefficient of x is ⅕
And in `6x + 7y` the coefficient of x is 6 and the coefficient of y is 7
For example, in `2x + 7` the coefficient of x is 2
And in `x/5` the coefficient of x is ⅕
And in `6x + 7y` the coefficient of x is 6 and the coefficient of y is 7
And not to be confused with a constant. A constant is a number by itself. A coefficient has a variable being multiplied by it.
Examples:
39x=30 3 is the constant and 9 is the coefficient.
Examples:
39x=30 3 is the constant and 9 is the coefficient.
Is it better to start on the right or left. Or does it matter?
It doesn't matter, for some people its easier for them to work out the problem if its on the left side. And some prefer it on the right side.
Thank you my teacher couldnt explain dat
u may wanna spell that right "dat" sounds like a gangster speaking :)
What is a coefficient?
A coefficient is the number that is being multiplied by a variable. For example in the term 5x, 5 is the coefficient.
What does y stand for?
Y is a common variable used to define one of the axes, as well as one of the ordered pairs.
do you have to always subtract with the first number before doing the other numbers?
generally but it can differ.
Can you add 6y instead of 7y?
No, adding 6y would not cancel out one of the y's or in other words a y variable would still be on both sides of the equation
It would be 20y=12y6 after adding 6y
It would be 20y=12y6 after adding 6y
where do I go to practice these problems on Khan Academy?
The videos are already mixed in with the appropriate exercises. Just look to the left of the video.
Here's one that applies to this video:
http://www.khanacademy.org/math/cceighthgrademath/cc8thsolvingequations/cc8thlinearequations/e/linear_equations_3
Here's one that applies to this video:
http://www.khanacademy.org/math/cceighthgrademath/cc8thsolvingequations/cc8thlinearequations/e/linear_equations_3
Go to the knowledge map and look up a section of math and click on you type of math
yes.....its called transposition
it means that you can take term(6y is a term, so is 6) and move it to the other side of the equation., but you have to do the opposite operation with it.
eg: 207y=6y6
207y6y=6
2013y=6
13y=620
13y=26
y=26/13
y=2
hope that helped
it means that you can take term(6y is a term, so is 6) and move it to the other side of the equation., but you have to do the opposite operation with it.
eg: 207y=6y6
207y6y=6
2013y=6
13y=620
13y=26
y=26/13
y=2
hope that helped
How do you know which number to take away? For example, when Sal added 6 to the right side. How do you know to do it on that side? I'm really confused on this, please help!
because, 6+6=0.if we add some other to 6 it would give us some other no.
In what case in real life would we get a question with variables on two sides?
It's good to know encase of exchanges. For example, if the CEO of a company wants 6 pears and $4 for 7 apples and $2, is it a worth exchange? If your apples are more than $2 each, it would most likely be worth it. Hope this helps! :D
I cant find any Multi step equations 1 that i can actually do. need help
How bout 10y(4x+5)3y
^
:
:
that isn't an equation ..this is one > 5=2x+14/12+11
:
:
that isn't an equation ..this is one > 5=2x+14/12+11
at 0:41 Why was he adding 7y on both the sides?
To change the equation so that there is only one yexpression.
He started with 20  7y = 6y  6
Adding 7y to both sides makes 20  7y + 7y= 6y  6 + 7y
(We know that the two sides are still equal to each other because has done the same thing to both sides.)
Simplifying, he gets 20 = 17y  6
He chose to add 7y to both sides so that the lefthand side became 20, an expression not involving y.
He started with 20  7y = 6y  6
Adding 7y to both sides makes 20  7y + 7y= 6y  6 + 7y
(We know that the two sides are still equal to each other because has done the same thing to both sides.)
Simplifying, he gets 20 = 17y  6
He chose to add 7y to both sides so that the lefthand side became 20, an expression not involving y.
Why would you start adding or subtracting on a certain side instead of the other? I get confused a lot for where i put the distributive variable and/or the symbol ( minus)when adding the opposite or even when you decide to multiply instead of divide or vice versa. Is there a rule for that? Say you have 7y+(6y)+5 =7x+8x4 i'm not sure if that would even work but it is just a example. *if using a certain law can you describe how that law is used with the problem and why you wouldn't use another law?
@modernmarvelz No problem
Thank you for such a great help kingstroker...greatly appreciated..
we dont care at all so go do us a favor and get penut butter
x or any letter is left, and nonletter is right, right?
Brian,
Technically it doesn't matter. To solve for an unknown the unknown variable could be on the left or on the right, as long as when you are finished it's ISOLATED (or "all by itself"). x=3 is the same thing as 3=x (that's called 'the symmetric property of equality'), so if you happen to isolate the variable on the right, you are allowed to reverse the direction of the equality. And you don't even need to wait until you've isolated everything to do the switch. For example, if you have 23=4x+2 you could write 4x+2=23… that's that same "symmetric property of equality" at work.
Now that said, out of habit most people tend to move the unknown to the left side and everything else to the right side. I think it just sounds better to say "x=3" than to say "3=x," but really all you need to do is isolate the unknown on ONE side. It doesn't specifically have to be the LEFT (although most people do chose to put the letters on the left!).
But in general, your basic approach is correct. You've got to isolate the variable to solve for it.
Technically it doesn't matter. To solve for an unknown the unknown variable could be on the left or on the right, as long as when you are finished it's ISOLATED (or "all by itself"). x=3 is the same thing as 3=x (that's called 'the symmetric property of equality'), so if you happen to isolate the variable on the right, you are allowed to reverse the direction of the equality. And you don't even need to wait until you've isolated everything to do the switch. For example, if you have 23=4x+2 you could write 4x+2=23… that's that same "symmetric property of equality" at work.
Now that said, out of habit most people tend to move the unknown to the left side and everything else to the right side. I think it just sounds better to say "x=3" than to say "3=x," but really all you need to do is isolate the unknown on ONE side. It doesn't specifically have to be the LEFT (although most people do chose to put the letters on the left!).
But in general, your basic approach is correct. You've got to isolate the variable to solve for it.
It can also be a letter can be right side?
What is a coefficient?
*A number multiplied to a variable in an expression* is a coefficient.
For example in 5x + 2y + 3 = 0 , 5 is the coefficent of x and 2 is the coefficent of y.
For example in 5x + 2y + 3 = 0 , 5 is the coefficent of x and 2 is the coefficent of y.
were is this usefull in life what job does this beside math teacher
This is a question that comes up a lot, and there are many different answers. Here are just a few (not all mine, just general answers which are often given).
 If you want to do anything science related, you'll need math. Physics relies on very advanced mathematics. Biology? You need mathematical models. Computer Science? That's all number systems. Etc. Even if you want to study something other than the hard sciences, there's still a very good chance you'll encounter maths. History, psychology, sociology, and many others use statistical, mathematical methods to process data. Bottom line: if you want higher education, you're very likely to need maths. Certainly not everything you'll learn in high school, but at least some of it.
 Mathematics is all around us. To truly understand the world, we need to understand mathematics. Without mathematics, we would still be cavemen; we would not be able to build houses without having them fall down. We would certainly not have electricity, let alone computers.
 In modern society it is as important to know at least basic mathematics as it is to know how to read and write. If you don't know anything about maths, you would be very bad at handling money for example.
 Even if you really don't need maths itself (or, more probable, some part of maths) studying it helps you build your analytical skills  which will certainly come in handy in any job and life in general.
For (even) more answers and examples check out http://mathforum.org/dr.math/faq/faq.why.math.html and http://www.mathguide.com/issues/whymath.html.
 If you want to do anything science related, you'll need math. Physics relies on very advanced mathematics. Biology? You need mathematical models. Computer Science? That's all number systems. Etc. Even if you want to study something other than the hard sciences, there's still a very good chance you'll encounter maths. History, psychology, sociology, and many others use statistical, mathematical methods to process data. Bottom line: if you want higher education, you're very likely to need maths. Certainly not everything you'll learn in high school, but at least some of it.
 Mathematics is all around us. To truly understand the world, we need to understand mathematics. Without mathematics, we would still be cavemen; we would not be able to build houses without having them fall down. We would certainly not have electricity, let alone computers.
 In modern society it is as important to know at least basic mathematics as it is to know how to read and write. If you don't know anything about maths, you would be very bad at handling money for example.
 Even if you really don't need maths itself (or, more probable, some part of maths) studying it helps you build your analytical skills  which will certainly come in handy in any job and life in general.
For (even) more answers and examples check out http://mathforum.org/dr.math/faq/faq.why.math.html and http://www.mathguide.com/issues/whymath.html.
Solving equations comes up everywhere in life. Even if you are a doctor, engineer, or architect. Math never goes away! (unfortunately)
i am still very confused about this topic. why would you go straight to adding 6 to cancel out the negative 6. shouldn't you take away positive six from the twenty to cancel out the negative six?
That's one way of looking at it. But it may not that obvious that what Sal did and what you're suggesting will yield exactly the same result.
For example
Sal did something like this
6y6+6 = 6y
And you're suggesting that it should be
6y6(6) = 6y
Notice that if you multiply the negative sign  with 6 it will yield +6 (since negative x negative= positive)
That's why:
6y6(6) = 6y6+6= 6y
For example
Sal did something like this
6y6+6 = 6y
And you're suggesting that it should be
6y6(6) = 6y
Notice that if you multiply the negative sign  with 6 it will yield +6 (since negative x negative= positive)
That's why:
6y6(6) = 6y6+6= 6y
Where did he learn all of this
He paid attention in school, did his work, and studied very hard.
207y=6y6 will equal 13=y right
I understand this
20  7y = 6y  6
Add 7y to both sides:
20 7y + 7y = 6y + 7y  6
20 = 13y  6
Add 6 to both sides:
20 + 6 = 13y  6 + 6
26 = 13y
Divide both sides by 13:
2 = y
Add 7y to both sides:
20 7y + 7y = 6y + 7y  6
20 = 13y  6
Add 6 to both sides:
20 + 6 = 13y  6 + 6
26 = 13y
Divide both sides by 13:
2 = y
How do you know which term to eliminate first, e.g 20 first or 7y.
It doesn't matter. Either way will give you the same answer:
207y = 6y 6
Eliminate 20 first:
20 20 7y = 6y  6 20
7y = 6y 26
7y  6y = 6y  6y 26
13y = 26
13y/(13) = 26/(13)
y = 2
Eliminate 7y first:
207y = 6y 6
20 7y + 7y = 6y +7y 6
20 = 13y 6
20 +6 = 13y  6 + 6
26 = 13y
26/13 = 13y/13
y = 2
207y = 6y 6
Eliminate 20 first:
20 20 7y = 6y  6 20
7y = 6y 26
7y  6y = 6y  6y 26
13y = 26
13y/(13) = 26/(13)
y = 2
Eliminate 7y first:
207y = 6y 6
20 7y + 7y = 6y +7y 6
20 = 13y 6
20 +6 = 13y  6 + 6
26 = 13y
26/13 = 13y/13
y = 2
What is the steps to solve equation that have variable on both sides
Say your expression is: 3x+20=8x10
add ten to both sides: 3x+30=8x
minus 3x from both sides:30=5x
divide both sides by 5: 6=x or x=6
and your equation is solved.
Hope this helps
add ten to both sides: 3x+30=8x
minus 3x from both sides:30=5x
divide both sides by 5: 6=x or x=6
and your equation is solved.
Hope this helps
I need help with this equation on my hm it's A=1/2Bh someone please help me.
This is the formula for triangle
207y=6y6 Step 1: +7y =+7y Simplify 20=13y6 Step 2: +6=+6
Simplify: 26=13y Step 3: 26/13=13y/13 Simplify and you're done! y=2
IS there another way to do this that was not in this video?
Simplify: 26=13y Step 3: 26/13=13y/13 Simplify and you're done! y=2
IS there another way to do this that was not in this video?
yes.....its called transposition
it means that you can take term(6y is a term, so is 6) and move it to the other side of the equation., but you have to do the opposite operation with it.
eg: 207y=6y6
207y6y=6
2013y=6
13y=620
13y=26
y=26/13
y=2
hope that helped
it means that you can take term(6y is a term, so is 6) and move it to the other side of the equation., but you have to do the opposite operation with it.
eg: 207y=6y6
207y6y=6
2013y=6
13y=620
13y=26
y=26/13
y=2
hope that helped
I think there is many ways but that one is the fastest and easiest.
I mean that long question hurt my brain loser
At :54, wouldn't it be 20y, because you get rid of the seven and you're left with y?
No, it would just be 20. The 20 didn't have a y to begin with, did it? if it doesn't start out with a variable it won't acquire one later in the problem.
i did not understand , n i have test next week
Just remember to keep the equation balanced. if you take away something from one side, take away from the other side too.
if you need more help just click on "comment" and ask.
if you need more help just click on "comment" and ask.
Solve equation 5m + 9 = 3(m  5) + 7
5m+9=3m15+7
2m+9=8
2m=17
m=17/2
2m+9=8
2m=17
m=17/2
Is there a certain side I should put the variable on? like which side would make solving the problem easier for me? (reference, 0:33)
Chole,
You can isolate the variable on either side.
Just choose the side that looks easiest to you.
Ifyour final answer is 17 = x you can always reverse that to x = 17. They both mean the same thing. Equality is commutative.
I hope that helps.
You can isolate the variable on either side.
Just choose the side that looks easiest to you.
Ifyour final answer is 17 = x you can always reverse that to x = 17. They both mean the same thing. Equality is commutative.
I hope that helps.
Help! I still don't understand it, I tried watching the video five times already but still don't understand!!
If you know how to solve equations with variables on one side, then you know that the purpose of doing this is to solve for the variable by isolating it on one side of the equation. The same is true for equations with variables on both sides.
*HOW TO SOLVE EQUATIONS WITH VARIABLES ON BOTH SIDES:*
_Use SADMEP ( or reverse PEMDAS): subtraction/addition, division/multiplication, exponents/roots, and then parentheses._
`Example:
3x + 8 + x = 12x + 84
1) *Combine Like Terms:*
Since 3x and x are on the same`**` side of the equation and they are like terms, you can simplify them.
3x + x = 4x, so the equation becomes:
4x + 8 = 12x + 84
2) *Subtraction/Addition:*
You need to make it so that there is only a variable on one side of the equation. To do this, you can subtract 4x from both sides of the equation.
4x  4x = 0
12x  4x = 8x, so the equation becomes:
8 = 8x + 84
3) *Subtraction/Addition:*
Since there is still a number on the side of the equation with the variable, you need to do more subtraction to get rid of it. You have to subtract 84 from both sides.
84  84 = 0
8  84 = 76, so the equation becomes:
76 = 8x
4) *Division/Multiplication:*
You need to make the 8x an x. Since 8 is being multiplied by x, you can do the opposite if multiplication (division) to get rid of it. You have to divide both sides by 8. 8x/8 = x
76/8 =9 1/2, so the solution is:
x = 9 1/2`
I hope this helps!
*HOW TO SOLVE EQUATIONS WITH VARIABLES ON BOTH SIDES:*
_Use SADMEP ( or reverse PEMDAS): subtraction/addition, division/multiplication, exponents/roots, and then parentheses._
`Example:
3x + 8 + x = 12x + 84
1) *Combine Like Terms:*
Since 3x and x are on the same`**` side of the equation and they are like terms, you can simplify them.
3x + x = 4x, so the equation becomes:
4x + 8 = 12x + 84
2) *Subtraction/Addition:*
You need to make it so that there is only a variable on one side of the equation. To do this, you can subtract 4x from both sides of the equation.
4x  4x = 0
12x  4x = 8x, so the equation becomes:
8 = 8x + 84
3) *Subtraction/Addition:*
Since there is still a number on the side of the equation with the variable, you need to do more subtraction to get rid of it. You have to subtract 84 from both sides.
84  84 = 0
8  84 = 76, so the equation becomes:
76 = 8x
4) *Division/Multiplication:*
You need to make the 8x an x. Since 8 is being multiplied by x, you can do the opposite if multiplication (division) to get rid of it. You have to divide both sides by 8. 8x/8 = x
76/8 =9 1/2, so the solution is:
x = 9 1/2`
I hope this helps!
Why is it better for all the Variables to be on the right hand side instead of the left hand side?
would you like x=4y+2 or 4y+2=x
Please Help?
would you like x=4y+2 or 4y+2=x
Please Help?
When it comes to actually solving the problem, it makes no difference at all. In the end 5=x and x=5 are equivalent statements. It's all based on your preference.
However, many people find it more convenient to put most of the stuff on the right side, with just a single variable on the left. This may be because in most countries around the world, people write from left to right. By putting the larger mess on the right side, you can simplify and equation without having to change a line every time. For example,
x=3y+8(y5)+219y+6(4y3)+82 = 3y+8y40+219y+24y18+82 =26y+45
However, many people find it more convenient to put most of the stuff on the right side, with just a single variable on the left. This may be because in most countries around the world, people write from left to right. By putting the larger mess on the right side, you can simplify and equation without having to change a line every time. For example,
x=3y+8(y5)+219y+6(4y3)+82 = 3y+8y40+219y+24y18+82 =26y+45
why didnt you just leave the equation at 5/3
u would have 2 have a a mixed number 4 that 1 2/3
So, let's say your problem has parentheses in it. For example:
8(3a+6)=9(2a4)
I understand you want to isolate the variable, but if you try to divide 9(2a4) by 8, I don't quite understand how that would work. Please help!
8(3a+6)=9(2a4)
I understand you want to isolate the variable, but if you try to divide 9(2a4) by 8, I don't quite understand how that would work. Please help!
I think that dividing will make it a bit more complex than it needs to be, so instead let's distribute what's outside of the parentheses.
8(3a+6)=9(2a4)
Distribute the 8 across the parentheses.
8(3a)+8(6)=9(2a4)
8(3a)=24a, 8(6)=48.
24a+48=9(2a4)
Distribute the 9 across the parentheses.
24a+48=9(2a)9(4)
9(2a)=18a, 9(4)=36.
24a+48=18a+36
Now this problem is a bit more like the one shown in the video.
Subtract each side of the equation by 18a+48.
6a=12
Divide each side of the equation by 6.
a=2
We have our solution!
I hope this example helps you solve linear equations with parentheses in them!
8(3a+6)=9(2a4)
Distribute the 8 across the parentheses.
8(3a)+8(6)=9(2a4)
8(3a)=24a, 8(6)=48.
24a+48=9(2a4)
Distribute the 9 across the parentheses.
24a+48=9(2a)9(4)
9(2a)=18a, 9(4)=36.
24a+48=18a+36
Now this problem is a bit more like the one shown in the video.
Subtract each side of the equation by 18a+48.
6a=12
Divide each side of the equation by 6.
a=2
We have our solution!
I hope this example helps you solve linear equations with parentheses in them!
So you only take away the number that is needed to isolate the variable? I always thought that you take away the number that is next to the variable.
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