Final answer:
A quadratic equation has no solutions when the discriminant is negative.
Step-by-step explanation:
A quadratic equation has no solutions when the discriminant is negative. The discriminant is the expression inside the square root in the quadratic formula. If the discriminant is negative, it means that there are no real solutions to the equation. For example, the equation x^2 + 4 = 0 has no solutions because the discriminant is 4 - 4(1)(4) = -12.