Calculate the discriminant, which is the part under the radical in a quadratic equation. Discriminant = b^2 - 4ac.
If the discriminant is positive, there are two real roots. The parabola crosses the x-axis, then crosses back.
If the discriminant is zero, there is one real root. The parabola touches the x-axis but does not cross it.
If the discriminant is negative, there are no real roots. The parabola never touches the x-axis.
In this equation, the discriminant is positive (172), so there are two roots.
