9. If f :(a,b)→ R has a relative extremum at c∈(a,b) , then either f′(c) 0 = or f′(c) does not exist. (A)O(B)X

18. Let g( x ) be the inverse function of the function f ( x )= xex , where x ≥ 0, i.e., g(f(x)) = x, and f(g(x)) = x for x ≥ 0. Which of the following items is the value of the integral ? (A) e – 1 (B) 1 (C) e (D) 1 + ln 2 (E) e 2 – 1