Question

If I add:
1+2x+6x^2+9x^3+7-2x+6x^2-9x^3...
won't I have to combine terms & then get
8+12x^2

cause won't the 9x^3 and the 2x cancel itself out???

Answer 1

You can only add/subtract "like" terms, that is, you can add x^3's to x^'s, x's to x's etc.

so yes, you are right.

Answer 2

thanks!!!