Question

use synthetic division to check -4 is a root of the polynomial expression: x^4+2x^3-9x^2-2x+8=f(x)

Answer 1

Hello,

........|x^4|x^3|x^2|x^1|x^0
........| 1..|.2...|.-9.|.-2.|.8
x=-3.| ....|.-4..|.8..|.4..|.-8
........| 1..|.-2..|.-1.|..2.|.0

x^4+2x^3-9x^2-2x+8=(x+3)(x^3-2x^2-x+2)+0
-4 is a root of the polynomial expression.