(a) using the chain rule, take the derivative of equation I

use equation II for a substitution into the derivative equation ... prove (a).

(b) use the result from (a) to find h'(x) and h''(x) ... show h'(0) = 0 and h''(0) < 0

(c) find g''(x) from equation II and show that g''(0) = 0 and that g'' changes signs at x = 0.