Math Problem Statement

what is the inverse of f(x)=8x+97x8f\left(x\right)=\frac{8x+9}{7x-8}

Solution

To find the inverse of the function f(x)=8x+97x8f(x) = \frac{8x + 9}{7x - 8}, we follow these steps:

Step 1: Replace f(x)f(x) with yy

We start by writing the equation as: y=8x+97x8y = \frac{8x + 9}{7x - 8}

Step 2: Swap xx and yy

To find the inverse, swap xx and yy: x=8y+97y8x = \frac{8y + 9}{7y - 8}

Step 3: Solve for yy

Now, solve for yy in terms of xx. First, eliminate the denominator by multiplying both sides of the equation by 7y87y - 8: x(7y8)=8y+9x(7y - 8) = 8y + 9 Distribute the xx on the left-hand side: 7xy8x=8y+97xy - 8x = 8y + 9 Move all terms involving yy to one side of the equation: 7xy8y=8x+97xy - 8y = 8x + 9 Factor out yy on the left-hand side: y(7x8)=8x+9y(7x - 8) = 8x + 9 Finally, solve for yy by dividing both sides by 7x87x - 8: y=8x+97x8y = \frac{8x + 9}{7x - 8}

Thus, the inverse function is: f1(x)=8x+97x8f^{-1}(x) = \frac{8x + 9}{7x - 8}

Conclusion:

The function f(x)=8x+97x8f(x) = \frac{8x + 9}{7x - 8} is its own inverse. That means f1(x)=f(x)f^{-1}(x) = f(x).

Would you like more details or have any questions?

Here are 5 related questions to expand on this topic:

  1. What are the conditions under which a function is its own inverse?
  2. How do we determine if a function is one-to-one (bijective)?
  3. Can you find the inverse of a quadratic function?
  4. How can you verify that two functions are inverses of each other?
  5. What is the graphical interpretation of inverse functions?

Tip: When solving for the inverse of a rational function, always ensure to check if the function is one-to-one to guarantee the existence of an inverse!

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Math Problem Analysis

Mathematical Concepts

Algebra
Inverse Functions
Rational Functions

Formulas

Inverse of a function: Swap x and y, solve for y
General form of a rational function: f(x) = \frac{ax + b}{cx + d}

Theorems

A function is its own inverse if f(f(x)) = x
A one-to-one function has an inverse

Suitable Grade Level

Grades 10-12