Find the critical points of the following functions and determine whether they are local maximums, minimums or otherwise using the second derivative test. If the second derivative test does not work, decide by computing the slope on either side of the point in question.
(a) f ( x ) = x^2 + 12x + 36
(b) g( x ) = (x+3)^4
(c) h( x ) = x-x^3
The solution contains the complete steps to arrive at the answer.