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**xxlvh** #1. The functions f and g are differentiable. For all x, f(g(x)) = x and g(f(x)) = x. If f(3) = 8 and f'(3) = 9, what are the values of g(8) and g'(8)?

#2. The following values are given:

f(2.5) = 31.25

f(2.8) = 39.20

f(3.0) = 45

f(3.1) = 48.05

For the function f which is differentiable. Both f and f' are strictly increasing on the interval 0 __<__ x __<__ 5. Which of the following could be the value of f'(3)?

(A) 20

(B) 27.5

(C) 29

(D) 30

(E) 30.5

- *originally, I tried to approximate f' by using the secant line and taking f(3.1) - f(2.8)/3.1 - 2.8 but ended up getting 29.5 as an answer..*