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, 5, right parenthesis, .(fg)(5).

f, of, x, equals, x, squared, plus, 7, x, plus, 4

f(x)=

x2+7x+4

g, of, x, equals, minus, 4, x, plus, 11

g(x)=

−4x+11

Solution

We are tasked with finding (fg)(5)(f \circ g)(5). This represents the composition of two functions f(x)f(x) and g(x)g(x), which means we first evaluate g(5)g(5) and then substitute that result into f(x)f(x).

Given:

  • f(x)=x2+7x+4f(x) = x^2 + 7x + 4
  • g(x)=4x+11g(x) = -4x + 11

Step 1: Find g(5)g(5)

Substitute x=5x = 5 into g(x)g(x): g(5)=4(5)+11=20+11=9g(5) = -4(5) + 11 = -20 + 11 = -9

Step 2: Find f(g(5))=f(9)f(g(5)) = f(-9)

Now substitute x=9x = -9 into f(x)f(x): f(9)=(9)2+7(9)+4f(-9) = (-9)^2 + 7(-9) + 4 First, calculate the terms: (9)2=81(-9)^2 = 81 7(9)=637(-9) = -63 f(9)=8163+4=22f(-9) = 81 - 63 + 4 = 22

Final Answer:

(fg)(5)=22(f \circ g)(5) = 22

Would you like further details or have any questions?

Here are 5 related questions:

  1. How do we interpret function composition?
  2. What happens when you reverse the order of composition, (gf)(x)(g \circ f)(x)?
  3. Can function composition be applied to non-linear functions?
  4. What is the significance of function domains in composition?
  5. How do you graph the composition of two functions?

Tip: When composing functions, always apply the inner function first and use its result for the outer function!

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Math Problem Analysis

Mathematical Concepts

Function Composition
Quadratic Functions
Linear Functions

Formulas

f(x) = x^2 + 7x + 4
g(x) = -4x + 11
(f ∘ g)(x) = f(g(x))

Theorems

Function Composition Theorem

Suitable Grade Level

Grades 9-12