Question

Roots of a quadratic equation are real when discriminant is ______________

(a) zero

(b) greater than zero

(c) less than zero

(d) greater than or equal to zero

The question was asked by my college professor while I was bunking the class.

This is a very interesting question from Quadratic Equations topic in chapter Complex Numbers and Quadratic Equations of Mathematics – Class 11

Answer 1

Right option is (d) greater than or equal to zero

The best I can explain: For a quadratic equation, ax^2+bx+c = 0, discriminant is b^2-4ac.

Roots are \(\frac{-b±\sqrt{b^2-4ac}}{2a}\). For real roots, radical must be non-negative i.e. discriminant should be greater than or equal to zero.