Math Problem Statement

Given the definitions of f, of, xf(x) and g, of, xg(x) below, find the value of left parenthesis, f, circle, g, right parenthesis, left parenthesis, minus, 3, right parenthesis, .(f∘g)(−3). f, of, x, equals, 2, x, squared, minus, 4, x, plus, 7 f(x)= 2x 2 −4x+7 g, of, x, equals, minus, 4, x, minus, 15 g(x)= −4x−15 Answer Attempt 2 out of 2

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Solution

To solve (fg)(3)(f \circ g)(-3), we need to first understand that (fg)(x)(f \circ g)(x) means f(g(x))f(g(x)), meaning we substitute g(x)g(x) into f(x)f(x).

Step 1: Find g(3)g(-3)

The function g(x)g(x) is given as: g(x)=4x15g(x) = -4x - 15 Substitute x=3x = -3 into g(x)g(x): g(3)=4(3)15=1215=3g(-3) = -4(-3) - 15 = 12 - 15 = -3

Step 2: Find f(g(3))=f(3)f(g(-3)) = f(-3)

Now, use g(3)=3g(-3) = -3 and substitute 3-3 into the function f(x)f(x). The function f(x)f(x) is given as: f(x)=2x24x+7f(x) = 2x^2 - 4x + 7 Substitute x=3x = -3 into f(x)f(x): f(3)=2(3)24(3)+7=2(9)+12+7=18+12+7=37f(-3) = 2(-3)^2 - 4(-3) + 7 = 2(9) + 12 + 7 = 18 + 12 + 7 = 37

Final Answer:

(fg)(3)=37(f \circ g)(-3) = 37

Would you like more details on how function composition works or have any other questions?

Here are five related questions for further practice:

  1. Find (fg)(2)(f \circ g)(2) using the same f(x)f(x) and g(x)g(x).
  2. If f(x)=3x2x+5f(x) = 3x^2 - x + 5 and g(x)=2x1g(x) = 2x - 1, find (fg)(1)(f \circ g)(1).
  3. What is (gf)(3)(g \circ f)(-3) using the same functions f(x)f(x) and g(x)g(x)?
  4. Find the inverse function of g(x)=4x15g(x) = -4x - 15.
  5. What is the domain of (fg)(x)(f \circ g)(x)?

Tip: In function composition, always start by evaluating the innermost function before applying the outer function.

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Math Problem Analysis

Mathematical Concepts

Algebra
Function Composition
Quadratic Functions
Linear Functions

Formulas

f(x) = 2x^2 - 4x + 7
g(x) = -4x - 15
(f ∘ g)(x) = f(g(x))

Theorems

Function Composition
Evaluation of Quadratic and Linear Functions

Suitable Grade Level

Grades 9-11