The discriminant for a quadratic polynomial gives you information about the polynomial's roots.
Given [tex]y=ax^2+bx+c[/tex], the discriminant is given by [tex]\Delta=b^2-4ac[/tex].
There are three possible conclusions you can draw. If [tex]\Delta>0[/tex], then the quadratic has two distinct real roots. If [tex]\Delta=0[/tex], then there is one repeated real root. If [tex]\Delta<0[/tex], then there are two complex (non-real) roots.
Since you found [tex]\Delta=72>0[/tex], that means that [tex]y[/tex] has two distinct real roots.
