a function f(x) is defined as f(x)= -8x^2. What is f(-3)?

Answer 1

All you need to do is substitute -3 in place of the x.

Answer 2

substitute -3 for every x in f(x) and simplify.

Answer 3

by now you've probably done it, but watch the "-" signs carefully

f(-3) = -8 * (-3)^2 = -8(9) = -72