-2x^2+8x-9+4x+7x^2+2

Add like terms

Step-by-step explanation:

You want to combine the squared, the variables, and the constants.

Combine -2x^2 and 7x^2 to get 5x^2

Then combine 8x and 4x which is 12x

Then combine -9 and +2 which is -7.

You should get 5x^2 + 12x - 7.

Keep in mind you can only combine like terms that are in the same equals barrier

For example: You can combine 8x + 3 + 2x = 0

but not 8x +3 = 2x +0 because they are on different sides of the equal sign.