Question

-5x^3+7x^2-8x-1
let x=-2

Answer 1

if they say let x=-2, then simply replace all the x's in the polynomial with -2, then evaluate

Answer 2

-5(-2)^3 +7(-2)^2 -8(-2) -1. The x^3 will be negative since it is a - times a - times a -. The x^2 will be positive. So we get 40 + 28 +16 -1 = 83