Question 65967
What you've done so far looks good!
Now that you have the x-coordinates of the maximum and minimum points of the curve, substitute these into the original cubic equation and solve for y.
You shoul get:
y = 36 and y = -14.8148...
You can see by inspection that the maximum is at (-2, 36) and the minimum is at (2.67, -14.815) 
Here's what the graph looks like:
{{{graph(300,200,-5,5,-20,40,x^3-x^2-16x+16)}}}