So start by putting the negative sign into the second polynomial.
-(6x^2-2x-9)
-6x^2+2x+9
then combine like terms with the first polynomial
5x^3+4x^2-6x^2-2x+9
and you will get
5x^3-2x^2+2x+9
Hope this helps you.
Neither of those work for that equation
Answer:

Step-by-step explanation:
Given : 
In order to find
we will substitute
for
in the given function, that is :


Go up or down two points away