[tex] b^{2} -4ac [/tex]
is used to determined the nature of the roots of a quadratic equation. It is called the discriminant.
If discriminant = 0 , then the roots are rational and equal
<0 (negative), then the equation has two distinct unreal roots
>0 (positive), then the equation has two real roots
↳ if it's a perfect square, then the roots are rational, otherwise, the roots are irrational