Find all the solutions to z^4 = -4 - 5z^2 in complex numbers.
Express all the solutions in the form a + bi, where a and b are real numbers.
z^4 + 5z^2 + 4 = 0
z^2 = x
x^2 + 5x + 4 = 0
(x + 4)(x + 1) = 0
x = -4 and -1
z^2 = -4
z^2 = -1
z = +-2i
z + +-i
