The polynomial [itex]z^4 + 2z^3 + 9z^2 - 52z + 200 = 0[/itex] has a root [itex]z=-3+4i[/itex]. Find the other 3 roots. Since the given root is complex, one of the other roots must be the complex conjugate of the given root. So the 2nd root is [itex]z=-3-4i[/itex]. To find the other roots, I divided the polynomial by [itex]z^2 + 6z + 13[/itex] (this is the product of the 2 known roots), which gave [itex]z^2 - 4z + 20[/itex] with remainder [itex]-120z - 60[/itex]. I don't know how to proceed from here because I haven't done many examples where you get a remainder after doing algebraic division. What should I do?