Question

Reduce −2 + b2 by 7 + b2.

Answer 1

To simplify (-2+b^2)-(7+b^2), first distribute the -1 to both terms in the second parenthesis. 
-2+b^2-7-b^2
Combine like terms.
-9 (1-1=0, so the b^2 is canceled out.)
(-2+b^2)-(7+b^2)=-9

Answer 2

b^2-2

-b^2-7

______

-9