If you've ever taken an algebra class, you've surely dealt with quadratic equations! In case you've forgotten, a quadratic equation is an equation in the form $$ax^2 + bx + c = 0$$. If we look at it as a parabola, for example $$y = ax^2 + bx + c$$, we can see that a quadratic equation is simply a parabola being solved for the X intercepts. If you remember the shape of a parabola (an open ended oval), you'll realize that there will normally be two answers. There are many ways to solve these equations, but the most certain way is to use the quadratic formula, as it works for every quadratic equation.
The quadratic formula is as follows: $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$ Notice the plus and minus sign together. You use this formula twice: once with the plus and once with the minus. Those two answers are the solution to the quadratic equation. Since there is a square root in the quadratic formula, sometimes there will also be 0 answers (negative value in the square root) or 1 answer (0 in the square root).