You can
put this solution on YOUR website!You have to combine like terms:
(4m^2-5m-6)+(3m^2+8m+9)
4m^2 + 3m^2 -5m +8m -6 +9
7m^2 +3m+3
By the way, for easier explanations to understand, see my Basic Algebra book that is now on sale CHEAP on Ebay. Search Ebay for "Rapalje."
R^2