Math Problem Statement

If f(x) = (x + 2) / (x + 3), which function is the inverse of f?

a. ( 1 + x ) ( 1 − x )

b. ( 3 x − 2 ) ( 1 − x )

c. ( 3 x − 1 ) ( x − 2 )

d. ( 3 x − 2 ) ( 1 + x )

Solution

To find the inverse of the function f(x)=x+2x+3f(x) = \frac{x + 2}{x + 3}, we follow these steps:

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

y=x+2x+3y = \frac{x + 2}{x + 3}

Step 2: Solve for xx

We need to express xx in terms of yy. Start by multiplying both sides by x+3x + 3 to eliminate the denominator: y(x+3)=x+2y(x + 3) = x + 2 Expand: yx+3y=x+2yx + 3y = x + 2 Now, isolate xx. First, bring all terms involving xx to one side and constants to the other: yxx=23yyx - x = 2 - 3y Factor out xx on the left-hand side: x(y1)=23yx(y - 1) = 2 - 3y Finally, solve for xx: x=23yy1x = \frac{2 - 3y}{y - 1}

Step 3: Swap xx and yy

To find the inverse function, replace yy with xx: f1(x)=23xx1f^{-1}(x) = \frac{2 - 3x}{x - 1}

Step 4: Compare with the given options

We see that this matches option b: f1(x)=3x21xf^{-1}(x) = \frac{3x - 2}{1 - x}

Thus, the inverse function is option b.

Would you like more details on any of these steps or have further questions?

Here are 5 related questions to explore:

  1. How can you verify if two functions are inverses of each other?
  2. What is the domain of the function f(x)=x+2x+3f(x) = \frac{x + 2}{x + 3}?
  3. How do you find the domain and range of inverse functions?
  4. What does it mean graphically for two functions to be inverses?
  5. Can every function have an inverse? Why or why not?

Tip: To verify if two functions are inverses, compose them. If f(f1(x))=xf(f^{-1}(x)) = x and f1(f(x))=xf^{-1}(f(x)) = x, they are indeed inverses!

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Algebra
Rational Functions

Formulas

Inverse function formula: f^{-1}(x) = (2 - 3x) / (x - 1)
f(x) = (x + 2) / (x + 3)

Theorems

Inverse Function Theorem
Properties of Rational Functions

Suitable Grade Level

Grades 9-12