how do I evaluate, -b^2-7b for b=-3

Question

I not sure what "for" means in algebra. I need to evaluate -b to the second power-7b for b=-3.

Answer 1

you have to write in the equation  (-3) instead of  b.

-(-3)^2-7(-3)=-9+21=12

because -(-3)^2=-9 and -7(-3)=21