Math Problem Statement

If f(X) = 2X + 1 and (f ∘ g)(X) = 3X + 2, then g(X) = …

Solution

We are given two functions f(x)=2x+1f(x) = 2x + 1 and (fg)(x)=3x+2(f \circ g)(x) = 3x + 2. We need to find g(x)g(x).

Step-by-Step Solution:

  1. Understanding the Composition: Since (fg)(x)=f(g(x))=3x+2(f \circ g)(x) = f(g(x)) = 3x + 2, we will substitute g(x)g(x) into f(x)=2x+1f(x) = 2x + 1 and set it equal to 3x+23x + 2.

  2. Setting Up the Equation: Let g(x)=ax+bg(x) = ax + b, where aa and bb are constants to be determined.

  3. Substitute g(x)g(x) into f(g(x))f(g(x)): Using f(x)=2x+1f(x) = 2x + 1: f(g(x))=f(ax+b)=2(ax+b)+1=2ax+2b+1f(g(x)) = f(ax + b) = 2(ax + b) + 1 = 2ax + 2b + 1

  4. Equating with 3x+23x + 2: We know that f(g(x))=3x+2f(g(x)) = 3x + 2. Thus: 2ax+2b+1=3x+22ax + 2b + 1 = 3x + 2

  5. Solve for aa and bb:

    • By comparing coefficients of xx, we get 2a=32a = 3, so a=32a = \frac{3}{2}.
    • By comparing the constant terms, we get 2b+1=22b + 1 = 2, so b=12b = \frac{1}{2}.
  6. Conclusion: Thus, g(x)=32x+12g(x) = \frac{3}{2}x + \frac{1}{2}.

Answer:

The correct answer is (c) 32x+12\frac{3}{2}x + \frac{1}{2}.

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

Related Questions to Explore:

  1. How do you find g(x)g(x) if f(g(x))f(g(x)) and f(x)f(x) are given but with different forms?
  2. What happens if f(x)f(x) is a quadratic function instead of linear?
  3. How can you verify your answer using substitution in composite functions?
  4. What is the role of inverse functions in such problems?
  5. How do you interpret and simplify composite functions with multiple operations?

Tip: When working with composite functions, try substituting variables or expressions directly to keep track of relationships between the functions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Composite Functions
Linear Equations

Formulas

f(g(x)) = 3x + 2
f(x) = 2x + 1

Theorems

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Suitable Grade Level

Grades 10-12