In below Problems
(a) Find all critical values, including those at which f '(x) is undefined.
(b) Find the relative maxima and minima, if any exist.
(c) Find the horizontal points of inflection, if any exist.
(d) Sketch the graph.
1. y = x3 + x2 - x - 1
2. f(x) = 4x3- x4
3. f(x) = x3 - 15/2 x2 - 18x + 3 / 2
4. y = 5x7 - 7x5 - 1
5. y = x2/3 -1