A continuous function h on [0,6] is differentiable on (0,6) and satisfies h(0)=h(3)=h(6)=10. In addition, h(1)=8 and h(5)=12. No further explicit formula is known.
a. Part 1: (a) Explain why there must be at least one value c1 in (0,3) with h′(c1)=0 and at least one value c2 in (3,6) with h′(c2)=0.
b. Part 2: (b) Prove that h has at least three stationary points in the open interval (0,6). Your argument should combine the conclusions from part (a) with appropriate reasoning about the overall behavior of h on [0,6].
c. Part 3: (c) Suppose further that h′′(x)<0 for all x in (2,4). Explain what this additional information implies about any stationary point that lies in that subinterval.