Equations for beginners
None
Watch the entire video
Simple equations of the form ax = b
Introduction to basic algebraic equations of the form Ax=B
Discussion and questions for this video
SIMPLIFY THE GIVEN ALGEBRIC EXPRESSION.
5x^2  7x^2
Do you understand English? Click here to see more discussion happening on Khan Academy's English site.
 say "Hey, this is going to be a 2".
 But what we'll do in this video is to think
 How to troubleshoot these problems systematically.
 Because what we'll find is that as more and more complicated
 are these equations, you will not be able to
 simply think about them and do them in your head
 So it is very important that you first understand how
 manipulate these equations, but even more important is
 understand what they really represent
 This literally just says 7 times x equals fourteen
 In algebra, do not write "times" ali
 When you write two numbers sidebyside or a number close
 a variable like this, that means you
 are multiplying
 It is just a shorthand, a notion of shorthand
 And usually we do not use the multiplication sign because
 He is confused, because x is the most common variable
 used in algebra
 And if I had to write 7 times x equals 14, if I write my
 sign of "times" or my x so a bit strange, it may seem
 as xx "or" times "times"
 So usually when you're dealing with equations,
 especially when one of the variables is an x, you
 would not use the traditional sign of multiplication
 You can use something like thisyou can use the point to
 represent the multiplication
 Then you can have 7 times is equal to 14
 But this is still a little unusual
 If you have something multiplied by a variable
 you just going to write 7 x
 This literally means 7 times x
 Now, to understand how you can manipulate this equation to
 solve it, let's see a thing
 Then 7 times x, what is this?
 This is the same asso I'll just rewrite this
 equation, but I'll rewrite it in visual form
 Soon, 7 times x
 Soon this literally means x added yourself 7 times
 This is the definition of multiplication
 So that's literally x x x x more more more more xlet's see,
 This is 5 x 'smore x more x
 Soon this right there is literally 7 x's
 This is 7 x, right there
 Let me rewrite it
 This right here is 7 x
 Now, this equation tells us that equals 7 x 14
 Then, just assuming this is equal to 14
 Let me draw 14 objects here
 So let me say I have 1, 2, 3, 4, 5, 6, 7, 8,
 9, 10, 11, 12, 13, 14
 So literally we're talking 7 x equals 14 things
 These are equivalent statements
 Now, the reason why I drew it that way is to
 you really understand what we will do when we
 We divide both sides by 7
 So let me erase it right here
 Then, the default step every timeI didn't want to do this,
 Let me do this, let me draw this last circle
 So in General, whenever you simplify an equation to a
 – a coefficient is only one number by multiplying
 the variable
 So, some number by multiplying the variable or we can call
 the coefficient times the variable is equal to
 something
 What you want to do is just divide both sides by 7
 in this case, or divide both sides by the coefficient
 So if you divide both sides by 7, what do you have?
 7 times something divided by 7 is only
 This original thing
 7 's if void and 14 divided by 7 is 2
 Then your solution is x equals 2
 But just to make this very tangible in your head, what
 is happening here is that when we divide both sides of the
 the equation by 7, we literally we divide both sides by 7
 This is an equation
 If you are saying that this is equal to it
 Anything I do on the left I will have to do on the right
 If they started being equal, I can't just do an operation
 on the one hand and in doing so continue being equal
 They were the same thing
 So if I split the left side by 7, so let me break it
 in seven groups
 Soon there are seven x's here, so that's one, two, three,
 four, five, six, seven
 So that's one, two, three, four, five, six, seven groups
 Now, if I divide it into seven groups, I also want to
 divide the right side into seven groups
 One, two, three, four, five, six, seven
 So, if this whole thing is equal to this whole thing, so each
 one of these small pieces that break, these seven pieces,
 shall be equivalent
 So that piece, we can say, is equal to that piece
 This piece is equal to this piecethey are
 all pieces are equivalent
 There are seven pieces here, seven pieces here
 Soon, every x must be equal to two of these objects
 Soon, we have x is equal to, in this casein this case
 We had the drawn objects where there are two
 of them. x is equal to 2
 Now, let's just use two other examples here only for
 really get into your mind that we are dealing with an equation,
 and any operation that you make on one side of the equation
 You must be on the other side
 So let me turn down a bit more
 So let's say that I have, I say, I have 3 x equals 15
 Now, once again, you may be able to do it in your head
 You're saying this is saying 3 times some
 number is equal to 15
 You can use your multiplication table 3 and figure out
 But if you just wanted to do this systematically, and that
 It is good to understand systematically, you say OK, this
 thing on the left is equal to this thing in the right
 What should I do with this thing on the left
 to have only one x there?
 Well, to have only the x, I need to divide it by 3
 and my motivation to do this and that ' 3 times
 anything divided by 3, 3 's Cancel and I stay
 with only the x
 now, 3 x 15 was equal to
 If I am splitting the left side by 3, for equality
 be satisfied, I need to divide the right side by 3.
 What this in '?
 The left side, the left side only
 an x, then we have just the x
 and the right side, and ' 15 divided by 3?
 This and ' 5.
 Now you could have done this equacao slightly
 different, even though they are equivalent
 If you start with 3 x equals 15, then we can say that
 instead of dividing by 3, I can just see me free to 3
 I can stick with the left side only equal to x, if I multiply both sides by
 the equacao by 1/3
 then if I multiply that estimate the equacao on both sides by 1/3
 This also works
 you say, 1/3 of 3 and 1.
 When we multiply this part, 1/3 times
 3, this and ' x
 1 x e ' equal to 15 times 1/3 and ' equal to 5
 and a 1 time x and ' the same as x, and this is the same thing
 where x is equal to 5
 and these two forms are equivalent to solve this
 If we divide both sides by 3, this and ' equivalent to
 multiply both side of equacao by 1/3
 Now let's do one more and I'll make it a little
 more complicated
 I'll modify the ft<u>min</u>word_len a little
 Let's say I have more 4y 2y = 18
 now, suddenly it's a little harder and
 to make this twin
 We are saying that something twice over 4 times that
 thing and ' equal to 18
 and ' harder to think that number is this
 You can try
 Let's say we have 1 is 2 times 4 times 1, 1 more
 and it does not work
 but let's consider systematically solve this
 You can try to guess and you can reach
 the answer, but how do we do it systematically?
 Let's show
 If two y's terms, what does that mean?
 This means literally that I have two y's summed up with one another
 IE and ' y y more
 and so I'm adding 4 y's
 that I am joining 4 y 's, who literally are four
 y's added with one another
 logo and ' y y y y more more more
 and that has to be equal to 18
 and that and ' equal to 18
 now, how many y's I have on the left?
 How many y's I have?
 I have one, two, three, four, five, six y's
 Thus we can simplify this as 6y and ' equal to 18
 and if you think about it, this makes sense
 so this here, the more 4 y and 2y ' 6y
 then more 4y 2y and ' 6y, and this makes sense
 If we have two more litters 4 stretchers, I'll
 have 6 stretchers
 If I have more y 2y's 4 ' s, I'll have 6 y's
 and this is equal to 18
 and now, we know how to do this
 If I have 6 times something equal to 18, if we divide the two sides
 the equacao by 6, do I solve the equacao
 then divide the left by 6, and divide the
 so I figur by law 6
 and we then y equals 3
 and you can try
 This and ' and ' cool about a equacao
 You can always check if you got the right answer
 Let's see if this works
 2 times 3 times 3 and 4 more ' to that?
 2 times 3, this and ' equal to 6
 and then 4 times 3 and ' equal to 12
 6 more ' equal to 12 and 18
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.
At 8:00, when he multiplies by 1/3 what is his motivation to choose that specific number? (Fraction) Can you multiply by a different number, a whole number, for example?
He's right until the end x=5 not 15.
@ 3:51, Sal uses the word Coefficient. What does that mean?
Coefficient is just the proper name for the number in front of the x. It's the amount that x is multiplied by.
7x=14, here, the coefficient of x is 7
7x=14, here, the coefficient of x is 7
A coefficient is the number that you multipy the variable by. As an example, in the problem that Sal was doing at 3:51 the coefficient would be 7. If you have any more questions feel free to ask me.
Like what Andrew and dominicsmithtuiala said, the coefficient is the number a variable is multiplied by. The variable could be anything; "a" or "b" or "z" or "θ" or "☺".
I LIKE THIS GUY BTW DO ANY OF U KNOW WHERE ARE THE MORE COMPLEX EQUATIONS LIKE FOR A SIXTH GRADER HYPATHETICALLY
If you are looking for ones harder than this, continue in the playlist. They'll get harder. :) It's surprising that you are into this in sixth grade, though. Keep working ahead. :)
In an otherwise elegant presentation, why use the jargon 'cancel out'? There is no such operation in my experience. It is a division with answer '1'. This, and 'changing signs when removing parentheses' (really multiplying by 1)are the two precursors of most poor algebra performance in lower grades.
This really helps me a lot! Are you going to make something like practice or exercises so that I can try it out? That would be awesome!!!
Thanks! LOL it was on the top page! Thanks for your help anywayzzzz <3
Yeah, you can do excercises as long as you're logged in. The link is at the top of the page where it says "Donate" and stuff; the link is http://www.khanacademy.org/exercisedashboard. The exercise module for this specific video is named "Linear equations 1", and the link is http://www.khanacademy.org/exercises?exid=linear_equations_1 .
no, that is a very confusing answer. here is one that will probably help more. x=2 because in the equation 7x=14, what does that mean? it really means that if you multiply x by 7 it equals 14. but how do you figure out what x is? well, just divide both sides by 7! so x=14 divided by 7
so x=2
so x=2
Because x can be anything and in that case its 2
Its 2 cause 7x 2= 14, but the 2 is hidden in a x so you don't know
do you have anything for yr6 primary because we haven't learned about x's and y's
isnt there a way to seperate the X's by using () as multiplicatoin too ?
do you mean distrubution?
SIMPLIFY THE GIVEN ALGEBRIC EXPRESSION.
5x^2  7x^2
If I have been diagnosed as having or being Mathematics dyslexic? Could Khan academy help me with this problem?
yes i agree.
sure as long as you take notes. write down formulas and steps and examples. something you can understand and maybe tell your school if they can let you use notes on math tests if not study really hard before one.
why dose he use different colors?
Do help you understand better, like let's say subtraction is pink and adding is blue, and there was a problem like 47+100+4030=? You could tell what they meant because of the colors. Of course this is more advanced math then that but you get the idea ;)
just because he feels like it
why we can no
i need some help with math the problem is: write the phrase as an algebraic expression. i need help with two problems. #12: the sum of n and the product of 3 and m #13: the quotient of 23 minus r and s
For number 12 you have to write it out like pemdas (as if a train was going right). So first it says "the sum of n" so u put (n + )Then it says "and the product of 3 and m" so it would be (n+3m)Hint:make sure to always know your math vocab in these types of problems it really helps.
For number 13 It first says "The quotient of 23" that means tht 23 is going to be divided by something (23/ )the next pt.is minus r and s meanin tht (23/rs) well thts it if u still dont understand please let me know thanx :)
For number 13 It first says "The quotient of 23" that means tht 23 is going to be divided by something (23/ )the next pt.is minus r and s meanin tht (23/rs) well thts it if u still dont understand please let me know thanx :)
excelente,pero no me sirve de nada ,no esta en español,cuando se traducira n todo al español de españa
Bueno, no es necesaria la traducción al español. El lenguaje de las matematicas es universal, pero dicho con todo respeto, no estaría mal ir aprendiendo inglés al mismo tiempo que álgebra.
factor the trinomial
s211s+18
s211s+18
he means that this is a video of equations not fatoring
Shouldn't this be in the comments section?
what does that mean
in this situation?
in this situation?
(S2)(S9).
This may not be the right place to ask that question.
This may not be the right place to ask that question.
what is he saying in 8:36?
Okay, so he showed before that 7x=14, right? So if you have seven x's, then when you add all of those x's together, you get 14. Here is the same thing, but with y, and with the y's broken into two parts. The first part is two y's (the blue ones), the second part is the four yellow y's. Well, the y's don't care what color they are, so you really have six y's. You can solve this just like he did with the x's in 7x=14. Hope this cleared up your understanding.
(2x to the 2nd power) then to the 3rd
((2x)^2)^3 = (2x)^6 = 2x . 2x .2x .2x .2x .2x = 64x^6 //64 times x to the power of 6
(2x^2)^3 based on the placement of the parenthesis that's how it reads.
((2x)²)³ = (2x)².(2x)².(2x)² = 4x².4x².4x² = 64x⁶
por favor necesito los videos en castellano, parce un material muy bueno pero no endiendo ingles. Muchas gracias
yo castellano no muy bien, lo siento...
how do i graph the inequality x+3y smaller or equal to6
The answer does need to be a graph in the xy plane because there are too many ordered pairs (x,y) that are solutions to this inequality to make a list of them. First sketch the line x+3y=6. It will serve as a boundary. Only the ordered pair below or on the line will satisfy the inequality. After you've shaded the solution area below the line, try picking out some points (x,y) and trying them in the inequality. You'll see that all the ones you pick below the line work and the points above the line don't work.
you have to isolate y. so subtract x and divide by 3. if you divide by a negative you have to flip the smaller or equal to, greater or equal to.
What Does "X" Mean? Could it Be Any Digit?
x could be any NUMBER, not just a digit. Numbers are anything like 248 or 12 or 7. Digits are the numerals 9 or 8 or 7 or 6 or 5 or 4 or 3 or 2 or 1 or 0. They are the symbols used to make numbers (though each of these symbols do each represent a number). There are three digits in the number "280". The digits are "2", "8", and "0". There are four digits in the number "3521". The important distinction is that "x" can be ANY number on its own. Not just "9,8,7,6,5,4,3,2,1,or 0".
In this case, x is a variable. It depends on the cases...
But, think that any word can be used instead of x. Such as y, z, k, h and so on.
It is just a kind of rule for everybody to easily know x is a variable... So, usually x or y is used.
But, think that any word can be used instead of x. Such as y, z, k, h and so on.
It is just a kind of rule for everybody to easily know x is a variable... So, usually x or y is used.
Yeah, X is just a symbol used for the unknown. It's not always X, you'll see Y a lot.
on simple equations from 5:58 where it discusses the y and 0 i get lost. I get this easily if I only use multiplication, but once it moves into the reasoning behind the answer from a division point I am lost. the same with the last part of the video when it breaks it down into the y.@10:24 when division is introduced, I get lost how this is reached, yet I am fine with the rest? Thank you.
wow. I never thought I would understand that even in high school. now i do. how cool is that?
Pretty cool if you ask me :)
whats the method that he is using at 4:16
Plese help me with this 5m5=58mm please help
5m5 = 58mm
5m5 = 59m
5m+9m5+5 = 0
14m = 0
m = 0/14
m= 0
Substituting m=0 into the equation
5x05 = 58x00
5 = 5
Hence, it's proved
5m5 = 59m
5m+9m5+5 = 0
14m = 0
m = 0/14
m= 0
Substituting m=0 into the equation
5x05 = 58x00
5 = 5
Hence, it's proved
5m+9m=5+5
14m=10
m=10/14
m=0.7143
14m=10
m=10/14
m=0.7143
first rewrite the equation as
2x+5x = 25
Now you can simplify it to be
7x = 25
Divide both sides by 7.
7x/7 = 25/7
so x=25/7 or 3 4/7
2x+5x = 25
Now you can simplify it to be
7x = 25
Divide both sides by 7.
7x/7 = 25/7
so x=25/7 or 3 4/7
Thatz great!!
why is a^1 = 1/a^1 anyone can proof pls??
a negative exponent represents an inverse so imagine a 1 underneath the "a^1". now all you do is flip it!
The negative exponents are a wonderful notation. Consider the rules for exponents: a^m * a^n = a^(m+n), and a^m/a^n = a^(mn). And that we know a^1 * 1/a^1 = a^1/a^1 = 1, using the quotient rule for exponents, then the product rule: a^1/a^1 = a^(11) = a^(1+ 1) = a^1 * a^1. So, a^1 * 1/a^1 = a^1 * a^1. And there you have it.
this y to the power of 7 multiplied by y to power of 5? Looking at it logically its actually
1/(y^7) * 1/(y^5) =
1/(y^7 * y^5) =
1/(y y y y y y y y y y y y)
1/(y^12)
or y^12
1/(y^7) * 1/(y^5) =
1/(y^7 * y^5) =
1/(y y y y y y y y y y y y)
1/(y^12)
or y^12
omg you are the best! god bless math and u!
that is unnecessary. his religious affiliation has no bearing in this context.keep religion out of mathematics please.
7x+12(2+8) please help
there's no () sign before the 7, so x is equal to [120/7]
127x is wrong. You cannot add 7x to 120. You could if the expression were 7x + 120x = 127x
7x + 12(2+8)=0
7x + 120=0
7x=120
x=  120/7= 17 1/7
Checking: L side = 7 (120/7) + 120= 120 =120 =0
R side= 0
L=R
7x + 120=0
7x=120
x=  120/7= 17 1/7
Checking: L side = 7 (120/7) + 120= 120 =120 =0
R side= 0
L=R
Istead of = should be + sign : (I pressed the wrong key): 120+120 =0
7x+12(2+8)
7x+12(10)
7x+120
127x
This should be correct
7x+12(10)
7x+120
127x
This should be correct
7X+12(2+8)=0
7X+12.10=0
7X+120=0
7X=120
X=120/7=17.142
X=+17.14
CHECK THIS
7X+12.10=0
7X+120=0
7X=120
X=120/7=17.142
X=+17.14
CHECK THIS
Write an equation based on the sentence: A number x is five more than times x minus three. Sove for the value of x
This question is badly phrased.
5(x3)=x
5x15=x
4x=15 divide both sides by 4
x=3.75 (3.753=0.75 0.75*5=3.75)
5x15=x
4x=15 divide both sides by 4
x=3.75 (3.753=0.75 0.75*5=3.75)
At 7:46, how does Khan know that you have to use 1/3 and multiply it on each side? Where does that 1/3 come from and how can you get it on other problems?
the 3x and 15 are actually, 3/1 x and 15/1 so when he used 1/3 times 3/1 it gave him 3/3=1 then he did it to the 15
Because its multiplying with variable(x) So u do the opposite and divide it from both side and there is always 1 with a variable
choose the one alternative that best completes the statment or answer the question.
solve the equation. 1/2 = r/11
solve the equation. 1/2 = r/11
1/2=r/11
or 1*11/2=r
or r=11/2
=r=5*1/2
or 1*11/2=r
or r=11/2
=r=5*1/2
1/2 = r / 11
(1/2) * 11 = (r/11) *11
(1/2) * 11 = r
r = 11/2 = 5,5
(1/2) * 11 = (r/11) *11
(1/2) * 11 = r
r = 11/2 = 5,5
This video helps me a lot!
No it doesn't
how do you know 7x = 14?
The x is a variable which can be any given # in this case it was 2...7multiplied by2 = 14
u divide 7 to both side because it is multiplying by variable and u got the ans:2
u subsitute x for 2 because u know that 7 x 2 = 14 so that's how u know
4x16=32
4x=32+16
4x=48 //:4
x=12
4x1216=32
4816=32
32=32
true
4x=32+16
4x=48 //:4
x=12
4x1216=32
4816=32
32=32
true
4x16=32
4x=3216
4x=16
x=4 :)
4x=3216
4x=16
x=4 :)
solve the equation and check your solution 8(x6)=3(x6)=
Check:
8[(6)6]=3[(6)6]
8(0)=3(0)
0=0
Dude, dont't make us do your homework?!
8[(6)6]=3[(6)6]
8(0)=3(0)
0=0
Dude, dont't make us do your homework?!
8(x6)=3(x6)
8x+48=3x18
8x3x=1848
11x=66
x=6
8x+48=3x18
8x3x=1848
11x=66
x=6
based on the previous question ,please help me to solve this problem,a square in the mall has side lengths 2.8X.an equilateral triangle shaped water feature with an area of 2.2x^2 is being cut out of the centre of the square.which is the remaining area of the square?A0.6x, B0.6x^2, C5.64x, D5.64^2
Area of square: (2.8x) squared = 7.84x^2
Now just subtract the area of the water feature: 2.2x^2
Resulting area is 5.64x^2
Now just subtract the area of the water feature: 2.2x^2
Resulting area is 5.64x^2
plus i was being sarcastic
Yu Yu Hakusho!
WE WERE TALKING ABOUT ANIME!!!and dunno about those teams
Anime isn't lame!!!just choose the good ones!!!
so wut, dont comment on this anymore then, u should comment on the ones that are saying "what is 1+1" or something
dude, im a genius
Do you like the a's or giants or yankees?
uh a bunch of people + me, and u just insulted all the people who like anime
why does Sal use a shorthand notation at 1:33
so it will help us understand the question and get us used to algebra.
In the case of 7x = 14, that is "shorthand notation" as he mentions. It is normal for you to use that form of notation whenever doing algebra. In fact, it is actually expected and it's harder to write 7 * x = 14 anyway. And... believe me, when you get to complicated equations, you probably wont want to write them that way either.
This is NOT about the video at all but I am curious: why does your streak reset when you get an answer wrong? I don't like to get answers wrong but it happens some times, and when i do get them wrong my streak resets! someone please answer my question!!!
To make you more proficient at whatever you're doing. Resetting forces you to start over and get through the whole thing without errors. It's a bit fun since it makes it more interesting for me.
just get the questions right
Ressetting the streak with just one wrong answer forces the student to really focus on getting the right answer, because it "counts." When I'm working problems, I have gotten answers wrong when I'm on the tenth question, and boy it gets my attention! Next time through I really am careful not to make any mistakes. :)
thanks for all of your answers!
well , u can use the scratch pad to avoid mistakes
how bout u ask me 1
6y=18
divide 18 by 6. 18/6=3
so, Y=3
divide 18 by 6. 18/6=3
so, Y=3
add 7 on both sides (b/s)
6y7+7=11+7
6y = 18 , here 7+7=0 or they are cancelled
divide by 6 on b/s
6y/6= 18/6
.'. y=3
6y7+7=11+7
6y = 18 , here 7+7=0 or they are cancelled
divide by 6 on b/s
6y/6= 18/6
.'. y=3
Is there a way to just follow the Algebra track? I am trying to get a credit in Algebra 1 and 2. I started by just following the suggested exercises, but today I found that I was doing Limits 1, 2, and 3, which are listed under Calculus. No wonder I didn't understand!
Thanks!
Thanks!
what program do you use to write with?
He uses a tablet
From the FAQ: "I use Camtasia Recorder ($200) + SmoothDraw3(Free) + a Wacom Bamboo Tablet ($80) on a PC. I used to use ScreenVideoRecorder($20) and Microsoft Paint (Free)."
instead of a mouse i think he uses a pad. and the program he uses to write it in idk. i think paint. and he records his screen with a screen recorder not sure which.
i dont have a question about simple equations. but i want to know if you have any videos on simple interest?
Where are the exercises?
Scroll up this page and hit PRACTICE, if you are new, watch a few videos and it will show you how you can track the work done here....Im new...and my question is are there exercises on more than MATH?
yes there is like history or biology
The exercise module is named "Linear equations 1" on the knowledge map (http://www.khanacademy.org/exercisedashboard) and the direct link is http://www.khanacademy.org/exercises?exid=linear_equations_1 . Hope this helped.
15 times x can be two for 30. That means two x can be 15 times to meet 30.
What is x equal to when 15x=90?
15x=90
x=90/15
x=6
x=90/15
x=6
15x = 90
=>15x/15 = 90/15
=> x = 6
=>15x/15 = 90/15
=> x = 6
the ans=15x=90
=15x6=90
=15x6=90
15x=90
x=90/15
x=6
x=90/15
x=6
15x=90
x=90/15
x=6
x=90/15
x=6
Really strange way..I mean, it's much more easy
7x = 14
x = 14/7
x = 2
7x = 14
x = 14/7
x = 2
I don't know which grade you are in...
But for a complete beginner, the method in the video will make complete sense and stick the stuff in the brain forever.
Back when I was in 5th grade my teacher just said,
7x=14
x=14/7
x=2
and thats the way you do it, I never got why we should do this, actually the above form is a minimized form of the full working
but when you master the idea of balancing the equation from an early stage, mathematics in higher level becomes a breeze.
7x=14, but we want the value of x,
so we have to divide 7x by 7..but to retain the integrity of the equation we must also divide 14 by 7 and this makes complete sense and clarifies the concept... If you get this concept clearly inequalities, and other not so straightforward operations will become very easy and natural.... and as you become proficient in this method, you don't need to write 7x/7 when you write..
hope I clarified my point..
But for a complete beginner, the method in the video will make complete sense and stick the stuff in the brain forever.
Back when I was in 5th grade my teacher just said,
7x=14
x=14/7
x=2
and thats the way you do it, I never got why we should do this, actually the above form is a minimized form of the full working
but when you master the idea of balancing the equation from an early stage, mathematics in higher level becomes a breeze.
7x=14, but we want the value of x,
so we have to divide 7x by 7..but to retain the integrity of the equation we must also divide 14 by 7 and this makes complete sense and clarifies the concept... If you get this concept clearly inequalities, and other not so straightforward operations will become very easy and natural.... and as you become proficient in this method, you don't need to write 7x/7 when you write..
hope I clarified my point..
would simple equations work with fractions?
CANT TOUCH THIS
If you follow the rules of math, it should work just fine with fractions. Just make sure that you are doing the math operations properly when you do so. Things get complicated when it comes to fractional equations.
not about simple equations.my quation is why you do not have interodaction to computer in your academy? may be it helps billions of people around the globe.i want to say you are wonderful creat in this world.keep it up.i am sure you will post interodaction to computer class very soon.you know why i took it in college but.....
OMG! your a life saver .. you just made my life soooo much easier thank youu soo much =)
i like pie. do you?
7ab+6c+7z=?
I havent heard simple equations explained quite like this before....I loved it!
Absolutly. I have tried SO MANY math programs since starting highschool three years ago, and have gotten stuck at the begining nearly every time because it didn't make sense. I got tired of trying and gave up. My mom saw an advertisement for Khan Academy while watching clips of the Tsunami in Japan and suggested I tried again. The first few videos I saw started about where I had been getting stuck before, and what I saw computed...yea!! Atlast, I might actually understand math! Thank you Mr. Khan!
this makes complete sense, if my teacher in 5th grade taugh me this my life would have been a lot easier, we didn't have internet back in those days (in my country anyway) so whatever the teacher said was correct and nothing else,
I had to stop believing my teachers and pursue knowledge on my own for months before I figured out what maintaining the integrity of equations meant...
7x=14
x=14/7 , this is like a formula to the beginner, it doesn't show the concept behind the operation...
but 7x = 14 , we want x, so we eliminate 7 by dividing 7x by 7, and to maintain the balance of the equation we also have to divide 14 by 7... THis is a clear concept and this makes equations at higher level a breeze....
I had to stop believing my teachers and pursue knowledge on my own for months before I figured out what maintaining the integrity of equations meant...
7x=14
x=14/7 , this is like a formula to the beginner, it doesn't show the concept behind the operation...
but 7x = 14 , we want x, so we eliminate 7 by dividing 7x by 7, and to maintain the balance of the equation we also have to divide 14 by 7... THis is a clear concept and this makes equations at higher level a breeze....
4x1/2x=8 what is x?
4x1=16x => 12x=1 x=1/12
4x1/2x=8
3 (and)1/2x=8
7/2x = 8 //I am changing to improper fraction and multiply both sides by 2
7x =16
x= 16/7 //it can be written x=2and 2/7 (2.2/7)
3 (and)1/2x=8
7/2x = 8 //I am changing to improper fraction and multiply both sides by 2
7x =16
x= 16/7 //it can be written x=2and 2/7 (2.2/7)
Multiply both sides by 2
2.4x2.1/2x=2.8
8xx=16 > 7x=16 > x=16/7
2.4x2.1/2x=2.8
8xx=16 > 7x=16 > x=16/7
x=2.2/7
4x  1/2x = 8
You need to solve first the left side, by multiplying all by 2:
(2 * 4x)  (2 * 1/2x) = (2 * 8)
8x  1x = 16
7x = 16
x = 16/7 OR x = 2.2857
You need to solve first the left side, by multiplying all by 2:
(2 * 4x)  (2 * 1/2x) = (2 * 8)
8x  1x = 16
7x = 16
x = 16/7 OR x = 2.2857
hey mr. khan i think thats your name whats the quadrastic formula again ?
If you're just memorizing this formula for a test, here it is. But if you actually want to learn it (and not forget), you need to be able to derive it. It's not that hard; just "complete the square" but use variables. You'll learn it eventually (http://www.khanacademy.org/video/quadraticformulaproof?playlist=Algebra). But here's the equation:
x=[b±√(b²4*a*c)]/2a , where the quadratic is in the form ax²+bx+c=0 . It gives 2 answers, and one of them could be complex.
Oh yeah, and his name is Sal.
x=[b±√(b²4*a*c)]/2a , where the quadratic is in the form ax²+bx+c=0 . It gives 2 answers, and one of them could be complex.
Oh yeah, and his name is Sal.
(2x2)3
12 12 12 12 12 12
(2x2)3
(4)3
12
This is how you get the answer by showing your work.
(4)3
12
This is how you get the answer by showing your work.
It would equal 12
2x2=4x3=12
this is the correct answer
this is the correct answer
2x2=4 so if I multiplied 4x3 it would equal 12
It is equal to 90.
a family spends 20% of its monthly income on food, 23% on rent, and 42%on other expenses and saves the balance. If the family saves $360 per month, what is its monthly income?
We have to sum these percentages to find out of saving percentage.
20+23+42=85
so saving percentage is : 15% which is $360
360x100/15 = 2400.
20+23+42=85
so saving percentage is : 15% which is $360
360x100/15 = 2400.
"U" suck not this!
u guys all suck!!!!!!!
yes true
Is this content closed captioned?
true ture
He is giving us a free education to use when ever! Really, have more respect.
PPlease Eexcuse Mme Ddear Aaunt Sally
parenthesis exponent multiply Division add Subtraction
U use this rule < side During it
parenthesis exponent multiply Division add Subtraction
U use this rule < side During it
That doesn't work
How does Add?
You can Google that one.
Is there any effect if you change the letter? I don't think so...Just checking ti be sure...
The variable? It's just a placeholder for a number so any letter would work.
Be careful though, special kinds of equations like slopeintercept format always use specific variables so y=mx+b will always look like y=5x+10, 5 always being m and 10 being b
Be careful though, special kinds of equations like slopeintercept format always use specific variables so y=mx+b will always look like y=5x+10, 5 always being m and 10 being b
But in general, any variable will work—the name should make it clear, it's "variable".
Is there any videos on intersections and unions? I cant seem to find any.
just type it in the search box
I tried that already.
sak wher r u living
4343434343343434343434343=jgyfrgjg
When should i start basically learning algebra, equations?
Normally, the basics actually begin in prealgebra (although I got equations like the one he mentioned in 5th grade). It gets more intense in ninth grade, so if you are in the 8th9th grade level, that's when you'll start seeing a lot of this stuff. It can't hurt to start earlier, though. It makes things easier later on.
Interestingly enough, in prealgebra, you are learning arithmatic principles that you'd want to know prior to beginning algebra. I personally found it a bit boring. When it gets to algebra, you are actually learning to apply what you've learned, and depending on what you know and how you think, it can be either much easier or much harder. In general, make sure you are able to understand prealgebra before you begin. If you are able to understand prealgebra, whatever your grade level may be, you should be ready to begin algebra. I would advise going in order through the playlist. If you need more help, you can work through the worked example playlists as well. Those are also useful.
Interestingly enough, in prealgebra, you are learning arithmatic principles that you'd want to know prior to beginning algebra. I personally found it a bit boring. When it gets to algebra, you are actually learning to apply what you've learned, and depending on what you know and how you think, it can be either much easier or much harder. In general, make sure you are able to understand prealgebra before you begin. If you are able to understand prealgebra, whatever your grade level may be, you should be ready to begin algebra. I would advise going in order through the playlist. If you need more help, you can work through the worked example playlists as well. Those are also useful.
RIGHT HERE, RIGHT NOW!!!
I want to know if 2 AA Batteries is more or less than 4 AAA Batteries?
4 AAA Batteries are a little bit more than 2 AA Batteries because they are both 1.5 volts and AA batteries are bigger than AAA batteries but 4 AAA batteries are bigger than 2 AA batteries by a minuet amount. I would say that AAA batteries have more of a kick than AA Batteries.
5x16.4/3.45=2x
5x  960 = 2x;
5x  2x = 960;
3x = 960;
x = 960 / 3;
x = 320!
5x  2x = 960;
3x = 960;
x = 960 / 3;
x = 320!
i thought it was please excuse my dear aunt sally not please excuse me dear aunt sally
it varies through the curriculums.
I thought it was Parachute Expert My Dear Aunt Sally.
is it the same way with fractions
Yes, these equations work the exact same way with fractions. Anything you do to one side you have to do to the other. I don't like fractional equations because they are harder to "eyeball" (guess at first glance), but they work the same way as far as how you solve them.
why did you multiply by 1/3?
Because, when you multiply 3x by 1/3, the 3x is actually 3/1 x, so when you multiply 1/3 to 3/1 you get 3/3, which equals to 1..... then you get 1x=5 then x=5 !!!yay
thank you when i asked my dad he had no idea what I was talking about
because trqainz areesssss epocalypse
DUde why do you multply by one third in your example?...........:)
thanks man.....
because the only thing that your doning is making the number next to x a fraction if it was 4x it would have been 1/4 etc
THIS IS NOT ANY HELP AND HIS VOUICE ISSSSS SOOOOOO IRITATINGGGG BLAHHHHHHH!!!!!!!!! IGO BANANNASSSS
did yuh just tell me wth wht tha hell ?????? and yes i am in schoo aw .. and yes his voice is iritating hey dude iam just speaking the truth dont get mad at me
1. his voice is not irritating 2. Are you even in, at least, middle school? if not, that might be hy you don't understand it
his voice is not irritating wth
Report a mistake in the video
Example:
At 2:33, Sal said "single bonds" but meant "covalent bonds."
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