Originally Posted by

**Siron** Yes, you can use the quadratic formula for every **quadratic** equation.

Now, it can be also important to know why you're calculating the discriminant. Probably you'll lear more about that.

But if you calculate: $\displaystyle 0=ax^2+bx+c$ which can be solved with the quadratic formula, you're calculing the point(s) where the parabola intersects the x-axis, because there $\displaystyle y=0$, now you can distinguish tree cases:

- $\displaystyle D<0$, the parabola doesn't intersects the x-axis at all, so there are no intersect points and so no solution.

- $\displaystyle D=0$, there parabola intersects the x-axis, there are two equal solutions.

- $\displaystyle D>0$, the parabola intersects the x-axis, there are two different intersect points and so two different solutions.