The first thing to do in this case is to write the polynomial in a factored form for the roots. We have then: (x-5) * (x + 4) = 0 Then, rewriting the quadratic equation: (x-5) * (x + 4) x ^ 2 + 4x -5x -20 x ^ 2 -x -20 answer: the quadratic equation whose roots are 5 and -4, and whose leading coefficient is 1 is x ^ 2 -x -20