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# Combining like terms

CCSS.Math:

## Video transcript

let's say that you started off with three apples and then I were to give you another seven another seven apples so my question to you and this might be very obvious is how many apples how many apples do you now have and I'll give you a second to think about that well this is fairly basic you had three apples now I'm going to give you seven more you now have three plus seven you now have ten apples but let's say I want to do the same type of thinking but I'm too lazy to write the word apples let's say instead of writing the word apples I just use the letter A and I say let's say and this is say a different scenario you start off with four apples you start off with four apples and to that I add another two apples I add another two apples how many apples do you now have instead of writing apples I'm just going to write a zero so how many of these A's do you now have and once again I'll give you a few seconds to think about that well this also might be a little bit of common sense for you if you had four of these apples or whatever these a is represented via four of them and then you add two more of them you're now going to have six of these apples but once again we started off assuming that A's represent apples but they could have represented anything if you have four of whatever a represents and then you have another two of whatever a represents you'll now have six of whatever a represents or if you just think of it if I have four A's and then I add another two A's I'm going to have six a is you can literally think of for A's as a plus a plus a plus a and if I do that if to that I add another two A's so plus a plus a that's two A's right over there how many A's do I now have well that's one two three four five six I now have six A's so thinking of it that way let's get a little bit more abstract let's say that I have five X's whatever X represents X could be some number so I have five of whatever that number is and from that I subtract I subtract two of what that number is what would this evaluate to how many of these exes how many of these X is what I now have so it's essentially 5 X minus 2 X is going to be what times X now once again I'll give you a few seconds to think about it well if I have five of something and I subtract two of those away I'm going to have three of that something left so this is going to be equal to 3 X 5 X minus 2 X is equal to 3 X and if you really think about what that means five X's are just X plus X plus X plus X plus X and then we're going to take away two of those X's we're going to take away 2 X's so take away 1 X take away 2 X's you are left you are going to be left with 3 x's