Math Problem Statement

If F(x) = 2x / (x + 3) and G(x) = x - 1, find a formula for (F o G)(x).

Solution

The problem in the image involves function composition. We are given two functions:

F(x)=2xx+3andG(x)=x1F(x) = \frac{2x}{x + 3} \quad \text{and} \quad G(x) = x - 1

We are tasked with finding (FG)(x)(F \circ G)(x), which is the composition of FF and GG, i.e., F(G(x))F(G(x)).

Step-by-step solution:

  1. Substitute G(x)=x1G(x) = x - 1 into F(x)F(x):

F(G(x))=F(x1)F(G(x)) = F(x - 1)

  1. Use the definition of F(x)=2xx+3F(x) = \frac{2x}{x + 3}:

Now, substitute x1x - 1 wherever there is xx in F(x)F(x):

F(x1)=2(x1)(x1)+3F(x - 1) = \frac{2(x - 1)}{(x - 1) + 3}

  1. Simplify the expression:

F(x1)=2(x1)x1+3=2(x1)x+2F(x - 1) = \frac{2(x - 1)}{x - 1 + 3} = \frac{2(x - 1)}{x + 2}

Expand the numerator:

F(x1)=2x2x+2F(x - 1) = \frac{2x - 2}{x + 2}

This is the formula for (FG)(x)(F \circ G)(x).

Answer:

The correct formula for (FG)(x)(F \circ G)(x) is:

c)2x2x+2\boxed{c) \frac{2x - 2}{x + 2}}


Would you like any additional details or explanations?

Here are 5 related questions you could explore:

  1. How do you evaluate the composition of two functions in general?
  2. What happens if G(x)=x+2G(x) = x + 2 instead of x1x - 1?
  3. Can the composition of functions be reversed, i.e., (GF)(x)(G \circ F)(x)?
  4. How does function composition differ from simple multiplication of functions?
  5. Can F(x)F(x) or G(x)G(x) ever lead to an undefined expression for certain values of xx?

Tip: When composing functions, always substitute carefully and simplify the resulting expressions step by step!

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra

Formulas

F(x) = 2x / (x + 3)
G(x) = x - 1
(F o G)(x) = F(G(x))

Theorems

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Suitable Grade Level

Grades 10-12