Math Problem Statement

Find the inverse function of fx=8/1+x

Solution

To find the inverse of the function f(x)=81+xf(x) = \frac{8}{1 + x}, follow these steps:

Step 1: Write the function in terms of yy

Let y=f(x)y = f(x), so: y=81+xy = \frac{8}{1 + x}

Step 2: Solve for xx

Now, solve for xx in terms of yy:

  1. Multiply both sides by 1+x1 + x to eliminate the denominator: y(1+x)=8y(1 + x) = 8

  2. Expand the left side: y+yx=8y + yx = 8

  3. Isolate yxyx by subtracting yy from both sides: yx=8yyx = 8 - y

  4. Solve for xx by dividing both sides by yy: x=8yyx = \frac{8 - y}{y}

Step 3: Write the inverse function

Now, replace yy with xx to represent the inverse function: f1(x)=8xxf^{-1}(x) = \frac{8 - x}{x}

So, the inverse function is: f1(x)=8xxf^{-1}(x) = \frac{8 - x}{x}


Would you like more details, or do you have any questions?

Here are some related questions you might find useful:

  1. What is the domain of f1(x)f^{-1}(x)?
  2. How do you verify that f(f1(x))=xf(f^{-1}(x)) = x and f1(f(x))=xf^{-1}(f(x)) = x?
  3. How does the behavior of f(x)f(x) compare to its inverse?
  4. What is the range of the original function f(x)f(x)?
  5. Can we determine any asymptotes for both f(x)f(x) and f1(x)f^{-1}(x)?

Tip: When finding an inverse, always swap xx and yy, then solve for the new yy. This represents the "undoing" of the original function.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Rational Equations
Algebra

Formulas

f(x) = 8 / (1 + x)
f^(-1)(x) = (8 - x) / x

Theorems

Inverse function theorem
Basic properties of rational functions

Suitable Grade Level

Grades 9-12