The value of c is 9. A perfect square trinomial can be written as (x + _ )^2 or (x - _)^2. In this equation the, missing entry must be able to be doubled and equal to 6. So the perfect square trinomial should be (x + 3)^2 or (x + 3)(x + 3). Then use FOIL to solve the polynomial, x^2 + 3x + 3x +9. C thus equals 9
