Math Problem Statement

The accompanying figure shows the graph of a function f over its domain −8 ≤ x ≤ 8. Explain why f has an inverse, and use the graph to find f^−1(2), f^−1(−1), and f^−1(0). Also, find the domain and range of f^−1 and sketch the graph of f^−1.

Solution

Let’s analyze the problem step by step based on the graph provided:

(a) Explain why ff has an inverse and find specific values.

  1. Why ff has an inverse: The graph of ff passes the horizontal line test (i.e., no horizontal line intersects the graph more than once). This indicates ff is one-to-one and therefore has an inverse.

  2. Find specific values using the graph:

    • f1(2)f^{-1}(2): Look at where y=2y = 2 on the graph. The corresponding xx-value is 88. Thus, f1(2)=8f^{-1}(2) = 8.
    • f1(1)f^{-1}(-1): Look at where y=1y = -1 on the graph. The corresponding xx-value is 4-4. Thus, f1(1)=4f^{-1}(-1) = -4.
    • f1(0)f^{-1}(0): Look at where y=0y = 0 on the graph. The corresponding xx-value is 00. Thus, f1(0)=0f^{-1}(0) = 0.

(b) Find the domain and range of f1f^{-1}.

The domain of f1f^{-1} is the range of ff, and the range of f1f^{-1} is the domain of ff.

From the graph:

  • The domain of f1f^{-1} is [2,2][-2, 2], because this is the range of ff.
  • The range of f1f^{-1} is [8,8][-8, 8], because this is the domain of ff.

(c) Sketch the graph of f1f^{-1}.

To sketch f1f^{-1}:

  • Reflect the graph of ff across the line y=xy = x.
  • Points such as (8,2)(-8, -2), (4,1)(-4, -1), (0,0)(0, 0), and (8,2)(8, 2) on ff become (2,8)(-2, -8), (1,4)(-1, -4), (0,0)(0, 0), and (2,8)(2, 8) on f1f^{-1}.

Would you like me to draw the graph of f1f^{-1} or explain these reflections further?


Follow-up Questions:

  1. Why is the horizontal line test essential for determining invertibility?
  2. Can a function fail the horizontal line test but still have an inverse if restricted to a subset of its domain?
  3. How does the reflection y=xy = x help construct the inverse function graphically?
  4. What would happen to the domain and range of f1f^{-1} if ff's domain were extended?
  5. How would discontinuities in ff affect f1f^{-1}?

Tip: Always verify a function is one-to-one before finding its inverse to ensure it exists.

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Math Problem Analysis

Mathematical Concepts

Functions and Inverses
Domain and Range
Graph Transformations

Formulas

Inverse Function Relation: f(f^−1(x)) = x and f^−1(f(x)) = x

Theorems

Horizontal Line Test for Invertibility

Suitable Grade Level

Grades 10-12