Math Problem Statement

Diketahui fungsi f dan g yang dinyatakan oleh f(x) = 2x + 3 dan g(x) = 3x - 2. Maka (g o f)(2) = ...

Solution

The problem asks us to find (gf)(2)(g \circ f)(2), given the following functions:

f(x)=2x+3f(x) = 2x + 3 g(x)=3x2g(x) = 3x - 2

The composition of functions (gf)(x)(g \circ f)(x) means that we first apply f(x)f(x) and then apply gg to the result of f(x)f(x). In mathematical terms:

(gf)(x)=g(f(x))(g \circ f)(x) = g(f(x))

Step 1: Find f(2)f(2)

Substitute x=2x = 2 into f(x)f(x):

f(2)=2(2)+3=4+3=7f(2) = 2(2) + 3 = 4 + 3 = 7

Step 2: Find g(f(2))=g(7)g(f(2)) = g(7)

Now, substitute x=7x = 7 into g(x)g(x):

g(7)=3(7)2=212=19g(7) = 3(7) - 2 = 21 - 2 = 19

Thus, (gf)(2)=19(g \circ f)(2) = 19.

Answer:

The correct choice is B. 1919.

Do you have any further questions or need more details? Here are 5 related questions to expand on this concept:

  1. How do you find the composition of two functions in general?
  2. If f(x)=x2+1f(x) = x^2 + 1 and g(x)=x3g(x) = x - 3, what is (gf)(x)(g \circ f)(x)?
  3. Can you reverse the composition, i.e., find (fg)(2)(f \circ g)(2) for the given functions?
  4. What is the geometric interpretation of function composition?
  5. What are some applications of function composition in real-life problems?

Tip: Always be careful with the order when composing functions—(gf)(x)(g \circ f)(x) is not the same as (fg)(x)(f \circ g)(x).

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Math Problem Analysis

Mathematical Concepts

Composition of Functions
Algebra

Formulas

(g o f)(x) = g(f(x))
f(x) = 2x + 3
g(x) = 3x - 2

Theorems

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Suitable Grade Level

Grades 10-12