what is the condition for roots to be equal to each other ??

It has?equal root?when ? a 2 + a + 2 = 0 . Hint: A quadratic equation has?equal roots?iff its discriminant is zero. A quadratic equation has?equal roots?iff these?roots?are both?equal?to the?root?of the derivative. Discriminant must be 0 in the case when two?equal?real?roots?in a quadratic equations.