Question

Me ajudem, Considere o polinômio p(x)= -x³-4x+5x²+20.Determine suas raízes.

Answer 1

$P(x)=-(x^3-5x^2+4x-20)\\ \\ P(x)=-[x^2(x-5)+4(x-5)]\\ \\ P(x)=-(x-5)(x^2+4)$

las raíces:

$-(x-5)(x^2+4)=0\\ \\ \boxed{x\in\left\{-\sqrt{2}\;i\,,\,5\,,\,\sqrt{2}\;i\right\}}$