Math Problem Statement

Jika f(x) = 3x + 1, g(x) = 1/(x - 1), dan h(x) = x^2 - 4, tentukan (h ∘ g ∘ f)(x) dan (f ∘ g ∘ h)(x)!

Solution

The question is asking to determine the composition of functions (hgf)(x)(h \circ g \circ f)(x) and (fgh)(x)(f \circ g \circ h)(x), given the functions:

f(x)=3x+1,g(x)=1x1,andh(x)=x24.f(x) = 3x + 1, \quad g(x) = \frac{1}{x - 1}, \quad \text{and} \quad h(x) = x^2 - 4.

Let's solve these step by step.

1. Finding (hgf)(x)(h \circ g \circ f)(x):

This is the composition of three functions, meaning we need to substitute one into the other in the specified order.

(hgf)(x)=h(g(f(x)))(h \circ g \circ f)(x) = h(g(f(x)))

Step 1: Find f(x)f(x):

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

Step 2: Find g(f(x))g(f(x)):

Substitute f(x)f(x) into g(x)g(x): g(f(x))=g(3x+1)=1(3x+1)1=13xg(f(x)) = g(3x + 1) = \frac{1}{(3x + 1) - 1} = \frac{1}{3x}

Step 3: Find h(g(f(x)))h(g(f(x))):

Substitute g(f(x))g(f(x)) into h(x)h(x): h(g(f(x)))=h(13x)=(13x)24=19x24h(g(f(x))) = h\left(\frac{1}{3x}\right) = \left(\frac{1}{3x}\right)^2 - 4 = \frac{1}{9x^2} - 4

So, (hgf)(x)=19x24(h \circ g \circ f)(x) = \frac{1}{9x^2} - 4

2. Finding (fgh)(x)(f \circ g \circ h)(x):

This is another composition in a different order:

(fgh)(x)=f(g(h(x)))(f \circ g \circ h)(x) = f(g(h(x)))

Step 1: Find h(x)h(x):

h(x)=x24h(x) = x^2 - 4

Step 2: Find g(h(x))g(h(x)):

Substitute h(x)h(x) into g(x)g(x): g(h(x))=g(x24)=1(x24)1=1x25g(h(x)) = g(x^2 - 4) = \frac{1}{(x^2 - 4) - 1} = \frac{1}{x^2 - 5}

Step 3: Find f(g(h(x)))f(g(h(x))):

Substitute g(h(x))g(h(x)) into f(x)f(x): f(g(h(x)))=f(1x25)=3(1x25)+1=3x25+1f(g(h(x))) = f\left(\frac{1}{x^2 - 5}\right) = 3\left(\frac{1}{x^2 - 5}\right) + 1 = \frac{3}{x^2 - 5} + 1

So, (fgh)(x)=3x25+1(f \circ g \circ h)(x) = \frac{3}{x^2 - 5} + 1

These are the final results:

  • (hgf)(x)=19x24(h \circ g \circ f)(x) = \frac{1}{9x^2} - 4
  • (fgh)(x)=3x25+1(f \circ g \circ h)(x) = \frac{3}{x^2 - 5} + 1

Would you like any further details or have any questions?

Related Questions:

  1. What is the general method for finding the composition of three functions?
  2. How do you interpret the result of a composition of functions graphically?
  3. What are the domain restrictions for the compositions (hgf)(x)(h \circ g \circ f)(x) and (fgh)(x)(f \circ g \circ h)(x)?
  4. How would the composition change if the functions were different?
  5. Can you decompose a complex function into simpler component functions?

Tip:

When performing function composition, always start with the innermost function and work your way outwards step by step. This systematic approach helps avoid mistakes.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra
Rational Functions
Quadratic Functions

Formulas

h(g(f(x))) = h(g(f(x)))
f(g(h(x))) = f(g(h(x)))

Theorems

Composition of Functions

Suitable Grade Level

Grades 10-12