Math Problem Statement

Select the graph of the inverse of the function f(x) = -2x + 4.

Solution

We are tasked with selecting the graph of the inverse of the function f(x)=2x+4f(x) = -2x + 4.

Step-by-Step Process:

  1. Original Function: The function given is f(x)=2x+4f(x) = -2x + 4. This is a linear function with a slope of -2 and a y-intercept of 4.

  2. Inverse Function: To find the inverse of f(x)=2x+4f(x) = -2x + 4:

    • Replace f(x)f(x) with yy: y=2x+4y = -2x + 4
    • Swap xx and yy: x=2y+4x = -2y + 4
    • Solve for yy: x4=2yx - 4 = -2y y=4x2y = \frac{4 - x}{2} or equivalently: y=2x2y = 2 - \frac{x}{2} This is the equation of the inverse function f1(x)=2x2f^{-1}(x) = 2 - \frac{x}{2}, which has a slope of 12-\frac{1}{2} and a y-intercept of 2.
  3. Graphing the Inverse:

    • The inverse function f1(x)f^{-1}(x) should have a line with a slope of 12-\frac{1}{2}, slanting downwards but less steep than the original function.
    • Its y-intercept is at y=2y = 2.

Matching the Graphs:

  • The correct graph should show a line with a y-intercept of 2 and a slope that descends less steeply compared to the original.

From the provided options:

  • Graph A: This has a negative slope, but it looks too steep to match f1(x)f^{-1}(x).
  • Graph B: This has a positive slope, which is incorrect since the inverse has a negative slope.
  • Graph C: This shows a line with a negative slope that matches the inverse function’s slope and has a y-intercept of 2.

Conclusion:

The correct graph is C.

Would you like any further details on this problem, or do you have any other questions?

Here are five related questions to deepen your understanding:

  1. How do you find the inverse of a linear function algebraically?
  2. What are the geometric properties of inverse functions on a graph?
  3. How does the slope of a line affect the steepness of a graph?
  4. Why is the line of an inverse function reflected over the line y=xy = x?
  5. Can every function have an inverse? Why or why not?

Tip: When graphing an inverse function, always remember that it reflects the original function across the line y=xy = x.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Functions
Inverse Functions
Graphing

Formulas

f(x) = -2x + 4
f^{-1}(x) = 2 - x/2

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 9-11