A quadratic equation can be solved using the discriminant. The roots of the quadratic equation: k1=2aD−b k2=2a−D−b where D = b^2 - 4*a*c - it is the discriminant. Because a=1 b=0 c=4 , then
D = b^2 - 4 * a * c =
(0)^2 - 4 * (1) * (4) = -16
Because D<0, then the equation has no real roots, but complex roots is exists.