Question

How do you factor b^2-81

Answer 1

The middle number is 0 and the last is -81Factoring means we want something like(b+_)(b+_)We need two numbers that add together to get and Multiply to get -81which are 9 and -9:9+-9 = 0 and 9*-9 = -81
Fill in the blanks in
(b+_)(b+_)
with 9 and -9 to get...(b+9)(b−9)
The answer is : (b+9)(b−9)