Math Problem Statement

Diketahui f(x) = 2x - 1 dan g(x) = 5x/(x + 1). Jika b adalah fungsi sehingga (g o h)(x) = x - 2, maka (h o f)(x) = ...

Solution

In the problem, you are given the following information:

  1. f(x)=2x1f(x) = 2x - 1
  2. g(x)=5xx+1g(x) = \frac{5x}{x + 1}
  3. (gh)(x)=x2(g \circ h)(x) = x - 2

You are asked to find (hf)(x)(h \circ f)(x).

Step-by-Step Solution:

  1. Understanding the composite function (gh)(x)(g \circ h)(x): (gh)(x)=g(h(x))=x2(g \circ h)(x) = g(h(x)) = x - 2 This means that g(h(x))=5h(x)h(x)+1=x2g(h(x)) = \frac{5h(x)}{h(x) + 1} = x - 2.

  2. Solve for h(x)h(x): Set up the equation using the expression for g(h(x))g(h(x)): 5h(x)h(x)+1=x2\frac{5h(x)}{h(x) + 1} = x - 2 Now, cross-multiply to solve for h(x)h(x): 5h(x)=(x2)(h(x)+1)5h(x) = (x - 2)(h(x) + 1) Expand the right-hand side: 5h(x)=(x2)h(x)+(x2)5h(x) = (x - 2)h(x) + (x - 2) Bring all terms involving h(x)h(x) to one side: 5h(x)(x2)h(x)=x25h(x) - (x - 2)h(x) = x - 2 Factor out h(x)h(x): h(x)(5(x2))=x2h(x)(5 - (x - 2)) = x - 2 Simplify the expression: h(x)(7x)=x2h(x)(7 - x) = x - 2 Solve for h(x)h(x): h(x)=x27xh(x) = \frac{x - 2}{7 - x}

  3. Find (hf)(x)(h \circ f)(x): Now, substitute f(x)=2x1f(x) = 2x - 1 into h(x)h(x): (hf)(x)=h(f(x))=h(2x1)(h \circ f)(x) = h(f(x)) = h(2x - 1) Substitute 2x12x - 1 into the expression for h(x)h(x): h(2x1)=(2x1)27(2x1)h(2x - 1) = \frac{(2x - 1) - 2}{7 - (2x - 1)} Simplify the numerator and denominator: h(2x1)=2x382xh(2x - 1) = \frac{2x - 3}{8 - 2x}

Thus, the expression for (hf)(x)(h \circ f)(x) is: 2x32x+8\frac{2x - 3}{-2x + 8}

Answer:

The correct choice is D.


Would you like more details or have any further questions? Here are five related questions to expand on this:

  1. What is the definition of a composite function, and how does it work?
  2. How would the solution change if g(x)g(x) were different?
  3. Can you explain the process of solving for h(x)h(x) in more detail?
  4. How can we verify that our solution for h(x)h(x) is correct?
  5. What are some common mistakes when working with composite functions?

Tip: When solving for a function within a composite, always carefully handle the algebraic manipulation to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Algebra
Composite Functions

Formulas

Composite function: (g ∘ h)(x) = g(h(x))
Cross-multiplication
Factorization

Theorems

Composite function theorem

Suitable Grade Level

Grades 10-12