How do I add the opposite of (9x^2-4x+8)-(12x^2-6x-3) and (x-2x^3+8-7x^2)-(8+5x-3x^3)

Question

Shadow · Answer

What do you mean by 'opposite'

Shadow · Answer

For adding these I think you just line up the like terms

So x^2 can only be added with other x^2, x added with other x, and constants added with other constants (ex: 3 + 5).

katkit25 · Answer

I knnow hhow to solve it
But i have no clues how to add the oppisite

Nnesha · Answer

$$\rm (9x^2-4x+8) \large \color{red}{-}(12x^2-6x-3) $$ which is same as $$\rm (9x^2-4x+8) \large \color{red}{-1}(12x^2-6x-3) $$
1st) distribute negative 1
2nd) combine like terms
if the signs are opposite you will subtract.