the gradient of a curve y=f(x) is given by dy/dx =ax(1-x) where a is a constant. the gradient of the curve at the point (2,-3) is -12 find the value of a and the equation of the curve.

i integrated it and subbed in the point(2,-3) to get 4a/2 -8a/3 +c =-3 i also know ax-ax^2=-12