Respuesta :

Answer:

Step-by-step explanation:

(3x^2 + 2x) + (-x +  9)             Remove the brackets

3x^2 + 2x - x + 9                    Watch out for the sign in front of the x

3x^2 + x +    9                         No more reduction can take place.

(-2x^2 + 5x - 7) + (3x + 7)       Remove the brackets

-2x^2 + 5x - 7 + 3x + 7

-2x^2 + 5x + 3x - 7 + 7           Combine

-2x^2 + 8x                              The 7s cancel -- they are of opposite signs.

No more reduction can take place. The powers on the variables have to be equal before any cancelation can take place.