use the rational zero theorem and descartes’ rule of signs to assist you in finding all real and imaginary roots for x^4+2^3-3x^2-4x+4=0

Answer 1

RRT says roots are ±1,±2,±4
DRT says there are at most 2 positive and 2 negative roots

so, a little synthetic division shows that 1 and -2 are both double roots