Help with math problem

Hi,

In one of Greg’s videos he said we could find out how many solutions are in an ax^2 + bx + c solution by solving: b^2 - 4ac. If it’s pos: 2 solutions, neg, 0 solutions, and 0, 1 solution.

However I’m having trouble, since the equation: x^2 + 5x + 7 has a negative value for b^2 - -4ac, but it still has solutions? Please help!

It doesn’t have any real solutions, but it has 2 complex solutions.