At the minimum point, the gradient will be zero, so we differentiate the equation, giving us dy/dx = 3e3x - 12e2x. If the gradient is zero at the minimum point, we can set dy/dx = 0, so 3e3x - 12e2x = 0. We rearrange to obtain 3e3x = 12e2x , and divide each side by 3 to get e3x = 4e2x. We can then divide each side by e2x to get ex = 4, and then take the natural log of each side to get x = ln4. To verify that the y co-ordinate is zero, we sub in ln4 for x in the original equation to obtain 64 - 96 +32 =0.