AP® Precalculus · Free response

An increasing function and a logarithmic function

write it first, then score yourself point by point

Q1: Function Concepts · Part A: graphing calculator allowed · 6 points

The question

Name: ______________________   Date: ____________   An increasing function and a logarithmic function (6 points)

Graph

The graph of ff, and the function gg

The graph of the increasing function ff consists of four line segments through (0,1)(0, 1), (2,2)(2, 2), (4,4)(4, 4), (6,5)(6, 5) and (8,8)(8, 8), for 0≤x≤80 \le x \le 8. The function gg is defined by g(x)=3ln⁡(x−1)−2g(x) = 3\ln(x - 1) - 2 for x>1x > 1.
−1123456789−1123456789xyf
  1. (A(i)) Find the value of g(f(6))g(f(6)). Give your answer correct to three decimal places. Show the work that leads to your answer. [1 point]

  2. (A(ii)) Find the value of f(g(e+1))f(g(e + 1)). Show the work that leads to your answer. [1 point]

  3. (B(i)) Find every value of xx for which g(x)=0.4xg(x) = 0.4x. Give each answer correct to three decimal places. [1 point]

  4. (B(ii)) Write the behavior of gg as xx approaches 11 from the right, using limit notation. [1 point]

  5. (C(i)) The function gg is invertible. Write an expression for g−1(x)g^{-1}(x). [1 point]

  6. (C(ii)) Find the exact value of g−1(f(4))g^{-1}(f(4)). [1 point]