Math Problem Statement

Use the functions f(x) = (1/8)x - 3 and g(x) = x^3 to find (g^{-1} o f^{-1})(-3).

Solution

The problem asks to find (g1f1)(3)(g^{-1} \circ f^{-1})(-3) using the functions:

  • f(x)=18x3f(x) = \frac{1}{8}x - 3
  • g(x)=x3g(x) = x^3

We will solve this step by step.

Step 1: Find the inverse of f(x)f(x)

Given f(x)=18x3f(x) = \frac{1}{8}x - 3, we want to find f1(x)f^{-1}(x).

  1. Set y=18x3y = \frac{1}{8}x - 3.
  2. Solve for xx in terms of yy:

y+3=18xy + 3 = \frac{1}{8}x x=8(y+3)x = 8(y + 3)

Thus, f1(x)=8(x+3)f^{-1}(x) = 8(x + 3).

Step 2: Find the inverse of g(x)g(x)

For g(x)=x3g(x) = x^3, we want to find g1(x)g^{-1}(x).

  1. Set y=x3y = x^3.
  2. Solve for xx in terms of yy:

x=y3x = \sqrt[3]{y}

Thus, g1(x)=x3g^{-1}(x) = \sqrt[3]{x}.

Step 3: Compute (g1f1)(3)(g^{-1} \circ f^{-1})(-3)

This means we first apply f1f^{-1} to 3-3, and then apply g1g^{-1} to the result.

  1. Compute f1(3)f^{-1}(-3):

f1(3)=8(3+3)=8(0)=0f^{-1}(-3) = 8(-3 + 3) = 8(0) = 0

  1. Compute g1(0)g^{-1}(0):

g1(0)=03=0g^{-1}(0) = \sqrt[3]{0} = 0

Thus, (g1f1)(3)=0(g^{-1} \circ f^{-1})(-3) = 0.

The answer is 0\boxed{0}.

Would you like further explanation or have any questions?

Here are 5 related questions:

  1. How do you find the inverse of a linear function?
  2. What are the steps to find the inverse of a cubic function?
  3. Why do we use function composition in mathematics?
  4. What are the properties of inverse functions?
  5. How do you verify if two functions are inverses of each other?

Tip: Always check that the domain and range of the function match the domain and range of its inverse when composing them.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Function Composition
Algebra

Formulas

f(x) = (1/8)x - 3
g(x) = x^3
f^{-1}(x) = 8(x + 3)
g^{-1}(x) = ∛x

Theorems

Inverse Function Theorem
Function Composition

Suitable Grade Level

Grades 9-12