Math Problem Statement

1 We have the function f(x) = (1/2)x+1.

a Find the inverse function of f(x) and call it g(x).

b Draw both functions in a coordinate system together with the line y = x.

C Use the graph to explain that f(x) and g(x) are inverse functions.

Solution

Part (a): Finding the inverse function of f(x)=12x+1f(x) = \frac{1}{2}x + 1

To find the inverse function, g(x)g(x), we follow these steps:

  1. Start with the equation for f(x)f(x): y=12x+1y = \frac{1}{2}x + 1

  2. Swap xx and yy, since the inverse function reverses the roles of xx and yy: x=12y+1x = \frac{1}{2}y + 1

  3. Solve for yy: x1=12yx - 1 = \frac{1}{2}y y=2(x1)y = 2(x - 1) y=2x2y = 2x - 2

Thus, the inverse function g(x)g(x) is: g(x)=2x2g(x) = 2x - 2

Part (b): Drawing both functions and the line y=xy = x

To plot the functions f(x)=12x+1f(x) = \frac{1}{2}x + 1 and g(x)=2x2g(x) = 2x - 2 along with the line y=xy = x, we need to sketch these graphs:

  1. f(x)=12x+1f(x) = \frac{1}{2}x + 1: This is a straight line with slope 12\frac{1}{2} and y-intercept at (0,1)(0, 1).

  2. g(x)=2x2g(x) = 2x - 2: This is another straight line with slope 22 and y-intercept at (0,2)(0, -2).

  3. Line y=xy = x: This is the identity line that bisects the coordinate plane, reflecting all points symmetrically.

These three lines should intersect at points where they reflect each other. I can create the graph for you if you upload a coordinate system or graphing tool.

Part (c): Explaining the Inverse Property Using the Graph

The graph visually shows that the functions f(x)f(x) and g(x)g(x) are mirror images of each other with respect to the line y=xy = x. Here’s why this confirms they are inverse functions:

  • For any point (a,b)(a, b) on the graph of f(x)f(x), the point (b,a)(b, a) lies on the graph of g(x)g(x).
  • This symmetry about the line y=xy = x means that g(f(x))=xg(f(x)) = x and f(g(x))=xf(g(x)) = x, which satisfies the definition of inverse functions.

Would you like to see a graph of these functions? I can also help with further details or specific clarifications.

Relative Questions:

  1. What is the domain and range of the inverse function g(x)=2x2g(x) = 2x - 2?
  2. How would the graph change if f(x)f(x) had a different slope?
  3. Can you verify that f(g(x))=xf(g(x)) = x algebraically?
  4. How does the y-intercept of f(x)f(x) relate to the x-intercept of g(x)g(x)?
  5. What happens to the inverse function when f(x)f(x) is not a linear function?

Tip:

When finding the inverse of a linear function, remember that the slope of the inverse is the reciprocal of the original function's slope.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Linear Functions
Coordinate Geometry

Formulas

Inverse function formula: g(x) = 2x - 2 for f(x) = (1/2)x + 1

Theorems

The concept of inverse functions and the reflection property across y = x

Suitable Grade Level

Grades 9-11