Roots of a quadratic equation are Real when the discriminant is ___________.

For a quadratic equation, ${\mathrm{ax}}^2+\mathrm{bx}+\mathrm{c}=0$ , discriminant(D) is ${\mathrm{b}}^2-4\mathrm{ac}$. 

Roots are $\frac{-\mathrm{b}\pm \sqrt{{\mathrm{b}}^2-4\mathrm{ac}}}{2\mathrm{a}}$. 

For real roots, discriminants have to be larger than or equal to zero.

i.e. $\mathrm{D} \ge 0$ .