Math Problem Statement

solve

Given that f(x) = 5/(x - 1) and g(x) = 4 - 2x, find: (a) f(f^(-1)(-2)), (b) g(g(3)), (c) a simplified expression for f(g(x)).

Solution

Let's solve the given problems step-by-step based on the image provided.


Given:

  1. f(x)=5x1f(x) = \frac{5}{x - 1}
  2. g(x)=42xg(x) = 4 - 2x

Part (a): f(f1(2))f(f^{-1}(-2))

Steps:

  1. Find f1(x)f^{-1}(x): To find the inverse, let y=f(x)y = f(x): y=5x1y = \frac{5}{x - 1} Solve for xx in terms of yy: y(x1)=5    x1=5y    x=5y+1y(x - 1) = 5 \quad \implies \quad x - 1 = \frac{5}{y} \quad \implies \quad x = \frac{5}{y} + 1 Thus, f1(x)=5x+1f^{-1}(x) = \frac{5}{x} + 1.

  2. Evaluate f1(2)f^{-1}(-2): Substitute x=2x = -2 into f1(x)f^{-1}(x): f1(2)=52+1=52+1=32.f^{-1}(-2) = \frac{5}{-2} + 1 = -\frac{5}{2} + 1 = -\frac{3}{2}.

  3. Find f(f1(2))f(f^{-1}(-2)): Substitute x=32x = -\frac{3}{2} into f(x)f(x): f(32)=5(321)=53222=552=2.f\left(-\frac{3}{2}\right) = \frac{5}{\left(-\frac{3}{2} - 1\right)} = \frac{5}{-\frac{3}{2} - \frac{2}{2}} = \frac{5}{-\frac{5}{2}} = -2.

Answer for (a): f(f1(2))=2f(f^{-1}(-2)) = -2


Part (b): g(g(3))g(g(3))

Steps:

  1. Find g(3)g(3): Substitute x=3x = 3 into g(x)g(x): g(3)=42(3)=46=2.g(3) = 4 - 2(3) = 4 - 6 = -2.

  2. Find g(g(3))g(g(3)): Substitute x=2x = -2 into g(x)g(x): g(2)=42(2)=4+4=8.g(-2) = 4 - 2(-2) = 4 + 4 = 8.

Answer for (b): g(g(3))=8g(g(3)) = 8


Part (c): Simplified expression for f(g(x))f(g(x))

Steps:

  1. Substitute g(x)=42xg(x) = 4 - 2x into f(x)f(x): f(g(x))=f(42x)=5(42x)1.f(g(x)) = f(4 - 2x) = \frac{5}{(4 - 2x) - 1}.

  2. Simplify the denominator: f(g(x))=542x1=532x.f(g(x)) = \frac{5}{4 - 2x - 1} = \frac{5}{3 - 2x}.

Answer for (c): f(g(x))=532xf(g(x)) = \frac{5}{3 - 2x}


Final Answers:

  1. (a): f(f1(2))=2f(f^{-1}(-2)) = -2
  2. (b): g(g(3))=8g(g(3)) = 8
  3. (c): f(g(x))=532xf(g(x)) = \frac{5}{3 - 2x}

Would you like me to go into further details or clarify any part? Here are 5 related questions to expand on this topic:

  1. How do you verify if two functions are inverses of each other?
  2. Can you compute the derivative of f(x)=5x1f(x) = \frac{5}{x - 1}?
  3. What is the range of f(x)=5x1f(x) = \frac{5}{x - 1}?
  4. How can the composition f(g(x))f(g(x)) be used in real-world applications?
  5. What happens to g(g(x))g(g(x)) if g(x)=ax+bg(x) = ax + b?

Tip: When finding inverse functions, always confirm that f(f1(x))=xf(f^{-1}(x)) = x and f1(f(x))=xf^{-1}(f(x)) = x.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Inverse Functions
Algebraic Simplification

Formulas

Inverse of a function: If y = f(x), solve for x to find f^(-1)(y).
Function composition: (f ∘ g)(x) = f(g(x))

Theorems

Properties of Inverse Functions

Suitable Grade Level

Grades 10-12