Question

If x = –3 is the only x-intercept of the graph of a quadratic equation, which statement best describes the discriminant of the equation?
The discriminant is negative.

The discriminant is –3.

The discriminant is 0.

The discriminant is positive

Answer 1

The discriminant equals to zero. Hope this is correct!

Answer 2

As x= -3 is the only x-intercept of the graph of a quadratic equation.

Which means that there are equal roots of the quadratic equation.

When the roots are equal then discriminant is zero.

$b^{2}-4ac = 0$

When the roots are not real then $b^{2}-4ac < 0$

When the roots are real and different (unequal) then  

$b^{2}-4ac > 0$

As in the given question x= -3 is the only root of the quadratic equation so the discriminant is zero