Question

as raizes da equacao x^2=+4x+8=0 corresponde
A)+_1i
B)-2+2i
C)3+-2i
D)4+4i
E)7i

Answer 1

$x^2+4x+8=0\\ \Delta=4^2-4.1.8=16-32=-16\ \to \ \sqrt\Delta=\sqrt{-16}= \\ =\sqrt{16\cdot(-1)}=4i\\ x_1=\frac{-4-4i}{2.1}=-2-2i, \ \ \ \ x_2=\frac{-4+4i}2=-2+2i\ \to \ \boxed{B}$