Math Problem Statement

Diketahuit f(x)=3x-1 dan g(x)=X²+3x+2 a. (fog) (x) b. (gof) (3)

Solution

Given two functions:

  • f(x)=3x1f(x) = 3x - 1
  • g(x)=x2+3x+2g(x) = x^2 + 3x + 2

Let's find:

a. (fog)(x)(fog)(x) or f(g(x))f(g(x))

To find (fog)(x)(fog)(x), we substitute g(x)g(x) into f(x)f(x).

  1. First, identify g(x)=x2+3x+2g(x) = x^2 + 3x + 2.
  2. Replace xx in f(x)f(x) with g(x)g(x):
    f(g(x))=3(g(x))1f(g(x)) = 3(g(x)) - 1
  3. Substitute g(x)g(x):
    f(g(x))=3(x2+3x+2)1f(g(x)) = 3(x^2 + 3x + 2) - 1
  4. Simplify:
    f(g(x))=3x2+9x+61f(g(x)) = 3x^2 + 9x + 6 - 1 f(g(x))=3x2+9x+5f(g(x)) = 3x^2 + 9x + 5

So, (fog)(x)=3x2+9x+5(fog)(x) = 3x^2 + 9x + 5.

b. (gof)(3)(gof)(3) or g(f(3))g(f(3))

To find (gof)(3)(gof)(3), we first calculate f(3)f(3) and then substitute it into g(x)g(x).

  1. Calculate f(3)f(3): f(3)=3(3)1=91=8f(3) = 3(3) - 1 = 9 - 1 = 8

  2. Substitute f(3)=8f(3) = 8 into g(x)g(x): g(8)=82+3(8)+2g(8) = 8^2 + 3(8) + 2 g(8)=64+24+2=90g(8) = 64 + 24 + 2 = 90

So, (gof)(3)=90(gof)(3) = 90.

Would you like more details, or do you have any questions?


Here are 5 related questions to consider:

  1. What would (fog)(2)(fog)(2) be for the same functions?
  2. How would (gof)(x)(gof)(x) be derived for these two functions in general?
  3. Can we find the inverse of f(x)f(x)? If so, what is it?
  4. What is the domain of g(x)g(x) for which (fog)(x)(fog)(x) is defined?
  5. How does (fog)(x)(fog)(x) behave as xx approaches infinity?

Tip: When evaluating compositions like f(g(x))f(g(x)), always substitute g(x)g(x) first and then simplify the expression step-by-step.

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Math Problem Analysis

Mathematical Concepts

Algebra
Function Composition
Polynomials

Formulas

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

Theorems

Function Composition

Suitable Grade Level

Grades 9-11