We can determine number of solutions of a quadratic equation using the discriminant.
If the discriminant is negative, there is no real solution, meaning that both solutions are complex.
If the discriminant is zero, there is 1 real solution, meaning that the other solution is complex.
If the discriminant is positive, there are 2 real solutions.
In this case, the discriminant is -1 which is negative. So there is no real solution. That means there are two complex solutions.
