Question

Determine if x – 5 is a factor of -2x^3+14x^2+24x+20. How do you know?

Answer 1

Use synthetic division

Answer 2

use the factor theorem

if x - 5 is a factor then x = 5 is a zero

so substitute x = 5 into the polynomial, is the answer is 0 then x - 5 is a factor

hope it helps. This method also avoids the need for synthetic or polynomial division.