SOLUTION: How do you know when to combine like terms?Why do we use like terms to add and subtract? Thanks

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Question 6362: How do you know when to combine like terms?Why do we use like terms to add and subtract?
Thanks
Answer by prince_abubu(198) About Me  (Show Source):
You can put this solution on YOUR website!
You would want to combine like terms in an expression to reduce the clutter. That is, once you've combined all the like terms by addition/subtraction, you've significantly "cleaned up" the expression.

Combining like terms is also a step (or series of steps) used in solving equations, especially if there are terms on both sides of the equation that are like-terms.

Say that you have 5*8 - 3*8. That's 40 - 24 = 16. We can say 5*8 - 3*8 = 2*8 (which = 16). It looks like we just took the 5 and subtracted 3 from it, then multiplied the difference by 8 - the number they are multiplied to in common. It works that way nicely. Suppose that we have 5x - 3x. That equals 2x. No matter what x value you choose, 5x - 3x = 2x.
Actually, in general, ax ± bx = (a ± b)x. Any a, b, and x will work.