Math Problem Statement

Find g^{-1}(x), where g(x) = \frac{5x}{9x - 5}, and also find the domain and range of g^{-1}(x).

Solution

Let's solve the problem step by step.

Step 1: Find the inverse function g1(x)g^{-1}(x).

Given g(x)=5x9x5g(x) = \frac{5x}{9x - 5}, we need to find the inverse function. To do this, we follow these steps:

  1. Start by replacing g(x)g(x) with yy:

y=5x9x5y = \frac{5x}{9x - 5}

  1. Swap xx and yy (this is a key step in finding the inverse):

x=5y9y5x = \frac{5y}{9y - 5}

  1. Solve for yy. Multiply both sides by 9y59y - 5 to get rid of the denominator:

x(9y5)=5yx(9y - 5) = 5y

  1. Expand the left-hand side:

9xy5x=5y9xy - 5x = 5y

  1. Rearrange the equation to group terms involving yy on one side:

9xy5y=5x9xy - 5y = 5x

  1. Factor out yy on the left-hand side:

y(9x5)=5xy(9x - 5) = 5x

  1. Solve for yy:

y=5x9x5y = \frac{5x}{9x - 5}

So, the inverse function is:

g1(x)=5x9x5g^{-1}(x) = \frac{5x}{9x - 5}

Step 2: Find the domain and range of the inverse function.

The domain of the inverse function g1(x)g^{-1}(x) is the same as the range of the original function g(x)g(x), and the range of the inverse function is the same as the domain of g(x)g(x).

  1. Domain of g(x)g(x):

    To find the domain of g(x)g(x), we must ensure the denominator does not equal zero:

9x50    x599x - 5 \neq 0 \implies x \neq \frac{5}{9}

Thus, the domain of g(x)g(x) is:

(,59)(59,)(-\infty, \frac{5}{9}) \cup (\frac{5}{9}, \infty)

  1. Range of g(x)g(x):

    The range of g(x)g(x) is all real numbers since g(x)g(x) is a rational function with no horizontal asymptotes restricting the range.

Thus, the range of g(x)g(x) is (,)(-\infty, \infty).

Step 3: State the domain and range of g1(x)g^{-1}(x).

  • The domain of g1(x)g^{-1}(x) is the range of g(x)g(x), which is (,)(-\infty, \infty).
  • The range of g1(x)g^{-1}(x) is the domain of g(x)g(x), which is (,59)(59,)(-\infty, \frac{5}{9}) \cup (\frac{5}{9}, \infty).

Final Answer:

g1(x)=5x9x5g^{-1}(x) = \frac{5x}{9x - 5}

  • Domain of g1(x)g^{-1}(x): (,)(-\infty, \infty)
  • Range of g1(x)g^{-1}(x): (,59)(59,)(-\infty, \frac{5}{9}) \cup (\frac{5}{9}, \infty)

Let me know if you'd like any clarifications, or further details on any step.


Here are 5 follow-up questions to expand your understanding:

  1. How do you verify that two functions are inverses of each other?
  2. What role does the domain restriction play in one-to-one functions?
  3. Can you find the asymptotes of both g(x)g(x) and g1(x)g^{-1}(x)?
  4. What happens to the range if we restrict the domain of g(x)g(x)?
  5. How does the graph of g(x)g(x) compare to the graph of g1(x)g^{-1}(x)?

Tip: Always check the function's domain and range before calculating its inverse, as certain values may make the function undefined.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Rational Functions
Domain and Range

Formulas

g(x) = \frac{5x}{9x - 5}
g^{-1}(x) = \frac{5x}{9x - 5}

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 10-12