Math Problem Statement

Match the graphs of f(x) = -3x - 1 and g(x) = 5x + 2 with the graphs of their inverses f^{-1}(x) and g^{-1}(x).

Solution

The image shows a problem asking to match the graphs of two functions, f(x)=3x1f(x) = -3x - 1 and g(x)=5x+2g(x) = 5x + 2, with the graphs of their inverses, f1(x)f^{-1}(x) and g1(x)g^{-1}(x).

We have four graphs displayed in the image, each in a different color: red, blue, black, and green. We are asked to match the colors of these graphs with the corresponding functions and their inverses.

Step 1: Finding the Inverses

  1. For f(x)=3x1f(x) = -3x - 1: To find the inverse, swap xx and yy and solve for yy: x=3y1x = -3y - 1 Solve for yy: x+1=3yx + 1 = -3y y=x+13y = -\frac{x + 1}{3} Therefore, the inverse function is: f1(x)=x+13f^{-1}(x) = -\frac{x + 1}{3}

  2. For g(x)=5x+2g(x) = 5x + 2: Similarly, swap xx and yy and solve for yy: x=5y+2x = 5y + 2 Solve for yy: x2=5yx - 2 = 5y y=x25y = \frac{x - 2}{5} Therefore, the inverse function is: g1(x)=x25g^{-1}(x) = \frac{x - 2}{5}

Step 2: Identifying the Graphs

Looking at the colors provided in the image:

  • Red, Blue, Black, Green

Given the equations and slopes:

  • The slope of f(x)=3x1f(x) = -3x - 1 is negative, so its graph will be steep and descending.
  • The slope of f1(x)=13x13f^{-1}(x) = -\frac{1}{3}x - \frac{1}{3} is also negative but less steep.
  • The slope of g(x)=5x+2g(x) = 5x + 2 is positive and steep.
  • The slope of g1(x)=15x25g^{-1}(x) = \frac{1}{5}x - \frac{2}{5} is positive but much less steep.

By visually comparing the slopes and y-intercepts in the graph:

  • The red line is the steep positive slope, matching g(x)=5x+2g(x) = 5x + 2.
  • The blue line has a steep negative slope, matching f(x)=3x1f(x) = -3x - 1.
  • The black line has a shallow positive slope, matching g1(x)=x25g^{-1}(x) = \frac{x - 2}{5}.
  • The green line has a shallow negative slope, matching f1(x)=x+13f^{-1}(x) = -\frac{x + 1}{3}.

Conclusion

  • f(x)=3x1f(x) = -3x - 1 matches the blue graph.
  • f1(x)=x+13f^{-1}(x) = -\frac{x + 1}{3} matches the green graph.
  • g(x)=5x+2g(x) = 5x + 2 matches the red graph.
  • g1(x)=x25g^{-1}(x) = \frac{x - 2}{5} matches the black graph.

Let me know if you'd like more details or further clarification!

Here are five questions that could expand this topic:

  1. How do you derive the inverse of a linear function in general?
  2. Why do the graphs of a function and its inverse reflect over the line y=xy = x?
  3. How would the inverses of non-linear functions differ from linear functions?
  4. Can you explain the importance of the slope and y-intercept when graphing linear functions and their inverses?
  5. How can you confirm graphically that two functions are indeed inverses of each other?

Tip:

When finding the inverse of a function, always remember to swap the roles of xx and yy and solve for the new yy. This method works well for all functions that have inverses.

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Math Problem Analysis

Mathematical Concepts

Functions
Inverse Functions
Graphing
Linear Equations

Formulas

f(x) = -3x - 1
g(x) = 5x + 2
f^{-1}(x) = -\frac{x + 1}{3}
g^{-1}(x) = \frac{x - 2}{5}

Theorems

Inverse of a Function
Graphing Linear Functions

Suitable Grade Level

Grades 9-12