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## Get ready for Algebra 1

### Unit 1: Lesson 7

Combining like terms# Intro to combining like terms

In simple addition we learned to add all the numbers together to get a sum. In algebra, numbers are sometimes attached to variables and we need to make sure that the variables are alike before we add the numbers. Created by Sal Khan.

## Want to join the conversation?

- Is zero prime, composite or neither?(3 votes)
- I think it's neither😁 Yeah, I know this was asked 9 years ago.(3 votes)

- so am i adding the X's for my answer?(3 votes)
- No, your adding the Chuck Norris's

I'm joking, yes you are adding the x's/variables(13 votes)

- You had to pick Chuck Norris

hahahahahahahahahahahahahahahahahaha

its beautiful!

but still

heres my question,

Could you take the exponents and divide them by itself if one of them is x^2 and it ends up as x=?(20 votes)- You can't find the value for anything by dividing it by itself. x^2 divided by x^2 equals 1. So, it still is x=?.

And yes, it's hilarious that he chose Chuck Norris as a variable.(3 votes)

- Is there a way to understand math better?(7 votes)
- the best way to understand math better is by using them regularly and developing understanding of numerical relations.(18 votes)

- I simply cannot figure out how to do this. I've watched the videos over and over and for some reason, it doesn't translate to the practice questions. I had the same problem in school. This has me doubting everything. Was enrolling in college a mistake? Why have I made near perfect grades in everything else, but this is like some other language?(10 votes)
- Yes, it is a very different language. But, to help me, I think of it as two different groups.

For example; 2x + 3x -7y = ?

In order for me to understand it, I group them into two different groups; the x's in one group and the y's in the other. I make as many groups as necessary. So, to solve the problem, 2x + 3x are one group, and -7y is another group. Then, I solve each group individually. 2x + 3x = 5x (Don't forget your variable!). -7y has nothing else to work. So, the answer becomes; 5x - 7y.

Hope that helped!(2 votes)

- How to solve this question 3x + 4 - 7x -6?(5 votes)
- Combine the two terms that contain "x".

Combine the two terms that don't contain "x".

Hope this helps.(8 votes)

- If my question is 20c+10b+25+5+30c, I know that I can add the 20c with the 30c bc the variables are the same, but I dont know what to do with the 10b. Someone please help me-(7 votes)
- 10b cannot be added to any of the other terms because they are different. You can add the 20c and 30c as well as the 25 and 5 which will leave you with the 10b as it is(2 votes)

- I've had to go back on this video over and over, I still don't understand. It may be the fact that I'm just stupid and too slow to catch up with everyone else.

But seriously, here's what I have to say; When you have a simple question, such as this: -n + (-3) + 3n + 5

How do you solve it? Actually, how do you solve most equations? If anyone has an answer, please help!(7 votes)- First, hello Ramiyah! In this video, what Sal is doing is just simplifying things up for the listeners. As you know, 2+3= 5, so 2x + 3x = 5x. A trick to solve this is to move all numbers with same variables to one side and set the other numbers with or without different variables to another. As an example, 3x + 7x +3 -6 + 8x. To solve, first move all numbers with same variables to one side, such as: 3x + 7x + 8x. Now, we only deal with these for now. You can ignore the variables for now, but add them later on the answer. So, 3 + 7 + 8 = 18, so the answer is 18x. Secondly, we put 18 x to our equation in the form of 18x + 3 - 6, Now, we deal with the other numbers without variables. so 18x + 3 - 6 = 18x + -3. So this is our answer!

Also, I'm sure that you are not stupid and too slow to catch up with somebody else, somebody stupid would not have asked for help at all. You can do anything that you set your mind to, just make sure to focus on it. If you have to watch it over and over again, just remember that this is part of your learning stage as a student. It does not matter if you are slower that anybody else, you are learning at your pace, and you can do it. I hope I was not much of a bother and that this helped!(2 votes)

- What is a
**Chuck Norris**(5 votes)- he is a famous actor and he was a popular subject for memes in the time that this video was made(3 votes)

- i don't have a question but dang there are comments from 9 years ago(5 votes)

## Video transcript

Let's say that I've
got 2 Chuck Norrises, or maybe it's Chuck Norri. And to that I am going to
add another 3 Chuck Norrises. So I'm going to add
another 3 Chuck Norrises. And this might seem
a little bit obvious, but how many Chuck
Norrises do I now have? Well, 2 Chuck Norrises,
we can represent this as literally a Chuck
Norris plus a Chuck Norris. So let me do that,
a Chuck Norris plus another Chuck
Norris, 2 Chuck Norrises. You could also do this
2 times Chuck Norris, and this is just another
way of representing it. And 3 Chuck Norrises-- you
could do that as a Chuck Norris plus a Chuck Norris plus
another Chuck Norris. And so we would
have a grand total-- and this might be
very simple for you. But you would have a
grand total of 1, 2, 3, 4, 5 Chuck Norrises. So this would be equal
to 5 Chuck Norrises. Now, let's get a little
bit more abstract here. Chuck Norris is a
very tangible thing. So let's go to a
little bit more of traditional algebraic notation. If I have 2x's and
remember, you could do this as 2x's or 2 times x. And to that, I would add
3x's How many x's do I have? Well, once again,
2x's, that's 2 times x. You could do that
as an x plus an x. We don't know what
the value of x is. But whatever that value is,
we can add it to itself. And then 3x's are they're
going to be that value. Let me do that in
that same green color. 3x's are going to be that
value plus that value plus whatever that value is. And so how many
x's do I now have? Well, I'm going to
have 1, 2, 3, 4, 5 x's. So 2x plus 3x is equal to 5x. And if you think about it, all
we really did-- and hopefully, you conceptually
get it-- is we just added the 2 numbers that
were multiplying the x. And these numbers, the 2 or the
3, they're called coefficients. Very fancy word, but it's
just this constant number, this regular number that's
multiplied by the variable. You just added the 2 and
the 3, to get your 5x. Now, let's think about
this a little bit more. Let's go back to this original
expression, the 2 Chuck Norrises plus 3 Chuck Norrises. Let's say, to that,
we were to add to some type of a-- let's we
were to add 7 plums over here. So this is my drawing of a plum. So we have 7 plums plus 2 Chuck
Norrises plus 3 Chuck Norrises. And let's say that I
add another 2 plums. I add another 2 plums here. So what this whole thing be? Well, I wouldn't add the 7
to the 2 to the 3 plus the 2. We're adding
different things here. You have 2 Chuck Norrises
and 3 Chuck Norrises, so they're still going to
simplify to 5 Chuck Norrises. . And then we would separately
think about the plums. We have 7 plums, and we're
adding another 2 plums. We're going to have 9 plums. Plus 9 plums, so this simplifies
to five Chuck Norrises and 9 plums. Similarly, over here,
instead of just 2x plus 3x, if I had 7y plus 2x plus 3x
plus 2y, what do I now have? Well, I can't add the
x's and the y's. They could very well
represent a different number. So all I can do is
really add the x's. And then I get the 5x. And then, I'd
separately add the y. If I have 7y's and to that I add
2y's, I'm going to have 9y's. If I have 7 of something
and I add 2 of something, I now have 9 of that something. So I'm going to have 9y's. So you add that. Do that in a different color. You add this and this. You get that. You add the x's. You get that right over there. So hopefully, that
makes a little sense. Actually I'll throw
out one more idea. So given this, what would happen
if I were to have 2x plus 1 plus 7x plus 5? Well, once again,
you might be tempted to add the 2 plus
the 1, but they're adding different things. These are 2x's. This is just the number 1. So you really just have
to add the x's together. So you're going to
say, well, I got 2x's. And I'm going to
add 7x's to that. Well, that means
I now have 9x's. And then, separately,
you'd say, well, I've got just the
abstract number 1. And then I've got another 5. 1 plus 5 is going
to be equal to 6.