Math Problem Statement

The function f(x) = 6x + 7 is one-to-one. a. Find an equation for f^{-1}, the inverse function. b. Verify that your equation is correct by showing that f(f^{-1}(x)) = x and f^{-1}(f(x)) = x.

Solution

To solve the given problem, we will address both parts step by step.


Part (a): Find an equation for f1f^{-1}, the inverse function.

The given function is:

f(x)=6x+7f(x) = 6x + 7

To find the inverse:

  1. Replace f(x)f(x) with yy: y=6x+7y = 6x + 7

  2. Swap xx and yy: x=6y+7x = 6y + 7

  3. Solve for yy to find the inverse: x7=6yx - 7 = 6y y=x76y = \frac{x - 7}{6}

Thus, the inverse function is:

f1(x)=x76f^{-1}(x) = \frac{x - 7}{6}


Part (b): Verify that your equation is correct by showing that:

  1. f(f1(x))=xf(f^{-1}(x)) = x
  2. f1(f(x))=xf^{-1}(f(x)) = x

Verify f(f1(x))=xf(f^{-1}(x)) = x:

Substitute f1(x)=x76f^{-1}(x) = \frac{x - 7}{6} into f(x)f(x): f(f1(x))=f(x76)f(f^{-1}(x)) = f\left(\frac{x - 7}{6}\right) f(x76)=6(x76)+7f\left(\frac{x - 7}{6}\right) = 6\left(\frac{x - 7}{6}\right) + 7 Simplify: 6x76+7=(x7)+7=x6 \cdot \frac{x - 7}{6} + 7 = (x - 7) + 7 = x Thus, f(f1(x))=xf(f^{-1}(x)) = x.

Verify f1(f(x))=xf^{-1}(f(x)) = x:

Substitute f(x)=6x+7f(x) = 6x + 7 into f1(x)f^{-1}(x): f1(f(x))=f1(6x+7)f^{-1}(f(x)) = f^{-1}(6x + 7) f1(6x+7)=(6x+7)76f^{-1}(6x + 7) = \frac{(6x + 7) - 7}{6} Simplify: 6x+776=6x6=x\frac{6x + 7 - 7}{6} = \frac{6x}{6} = x Thus, f1(f(x))=xf^{-1}(f(x)) = x.


Final Answer:

  1. The inverse function is: f1(x)=x76f^{-1}(x) = \frac{x - 7}{6}

  2. The verification shows: f(f1(x))=xandf1(f(x))=xf(f^{-1}(x)) = x \quad \text{and} \quad f^{-1}(f(x)) = x

Would you like further clarifications or additional examples?


Related Questions:

  1. What are the conditions for a function to have an inverse?
  2. Can the inverse of f(x)=ax+bf(x) = ax + b always be expressed in the same form?
  3. What happens if a function is not one-to-one? Does it have an inverse?
  4. How does the graph of a function compare to the graph of its inverse?
  5. Can we verify inverses graphically using reflection across the line y=xy = x?

Tip:

When finding the inverse of a function, always verify by substituting into both compositions f(f1(x))f(f^{-1}(x)) and f1(f(x))f^{-1}(f(x)) to ensure correctness.

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions and Inverses
Verification of Inverse Functions

Formulas

y = mx + b (linear function equation)
f^{-1}(x) = (x - b) / m

Theorems

One-to-One Function Inverse Property

Suitable Grade Level

Grades 9-11