Question 374963
(-8b^2+9b+4)-(9b^2+4)
distribute the "negative sign":
(-8b^2+9b+4)-9b^2-4
removing the parenthesis
-8b^2+9b+4-9b^2-4
grouping like-terms:
-8b^2-9b^2+9b+4-4
(-8b^2-9b^2)+9b+(4-4)
-17b^2+9b+0
-17b^2+9b