9. Subtract

 

(x^2+7x-8)-(2x^2-4x+5)

The second polynomial is being subtracted, so when we remove

parentheses, we need to change the signs on all the terms inside.

 

x^2+7x-8-2x^2+4x-5

 

Now combine like terms

 

-x^2+11x-13

 

When we use the vertical format, we simply change the sign on

the terms in the polynomial we are subtracting when we write it

underneath the other polynomial.

 

The same problem in vertical format