Math Problem Statement

find f^-1(x) of this function: f(x) = (2x+3)/(x-4)

Solution

To find the inverse function f1(x)f^{-1}(x) for the given function f(x)=2x+3x4f(x) = \frac{2x+3}{x-4}, follow these steps:

Step 1: Set y=f(x)y = f(x)

We start by rewriting the function with yy in place of f(x)f(x): y=2x+3x4y = \frac{2x + 3}{x - 4}

Step 2: Swap yy and xx

To find the inverse, swap yy and xx: x=2y+3y4x = \frac{2y + 3}{y - 4}

Step 3: Solve for yy

Now, solve this equation for yy:

  1. Multiply both sides by y4y - 4 to eliminate the denominator: x(y4)=2y+3x(y - 4) = 2y + 3
  2. Expand the left side: xy4x=2y+3xy - 4x = 2y + 3
  3. Move all terms involving yy to one side and constants to the other: xy2y=4x+3xy - 2y = 4x + 3
  4. Factor out yy on the left side: y(x2)=4x+3y(x - 2) = 4x + 3
  5. Solve for yy: y=4x+3x2y = \frac{4x + 3}{x - 2}

Step 4: Write the inverse function

Thus, the inverse function is: f1(x)=4x+3x2f^{-1}(x) = \frac{4x + 3}{x - 2}

Would you like more details or have any questions?

Related Questions:

  1. How can you verify that a function and its inverse are correct?
  2. What is the domain of f(x)f(x) and f1(x)f^{-1}(x)?
  3. How does the graph of a function compare to the graph of its inverse?
  4. Can all functions have an inverse? If not, why?
  5. What are the key properties of inverse functions?

Tip:

When finding an inverse function, always check the domain and range to ensure the inverse makes sense in context!

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Math Problem Analysis

Mathematical Concepts

Algebra
Inverse Functions
Rational Functions

Formulas

Inverse function: Swap x and y and solve for y
f(x) = (2x + 3) / (x - 4)

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 10-12