i have a doubt;
The curve with the equation y=k(x^3 -3x^2 -24x +c)
where k and c are non-zero constants, has two stationary points. show that the coordinates of one stationary point are (4, kc-80k ), and find, in a similar form the coordinates of the second stationary point. given that the mid-point of the line joining the two stationary points lies on the x-axis, show that c=26. given further that the tangent to the curve at the point of which x=2 passes through the point (5,-140), find the exact value of k.?