I know this is probably really easy, but i just can't figure it out.. 1. The problem statement, all variables and given/known data Find values of k for which (5 + 4x - x^2 = k) has equal roots. I know the answer is k = 9 but i don't know how to get there.. 2. Relevant equations ax^2 + bx + c = 0 Discriminant = b^2 - 4ac I know the discriminant has to equal 0 for the equation to have equal roots.. 3. The attempt at a solution But i get Discriminent = 36..? and the roots equaling -1 or 5..? Im lost.