x^4-4x^3+3x^2+8x-16

Question

Find the zeroes given one is x^2-x-4.

I don't know what to do now. i tried synthetic division. pls help : D

Answer 1

synthetic division only work for linear factors.

Long division yields

x^4-4x^3+3x^2+8x-16 = (x^2-x-4)(x^2-3x+4)

finding the zeros now is easy.
Right?