Math Problem Statement

Determine the following based on the functions: f(x) = 4 - 2x, g(x) = x^2 + 5, h(x) = (x - 6) / 7. a) f(g(-3)) = -24 b) g ∘ h(20) c) h(f(g(3))).

Solution

Let's break down the functions and solve each part of the question step by step.

We are given three functions:

f(x)=42xf(x) = 4 - 2x g(x)=x2+5g(x) = x^2 + 5 h(x)=x67h(x) = \frac{x - 6}{7}

Part a: f(g(3))f(g(-3))

We are told f(g(3))=24f(g(-3)) = -24, but let's confirm this.

  1. First, find g(3)g(-3): g(x)=x2+5g(x) = x^2 + 5 Substituting x=3x = -3: g(3)=(3)2+5=9+5=14g(-3) = (-3)^2 + 5 = 9 + 5 = 14

  2. Now, find f(14)f(14): f(x)=42xf(x) = 4 - 2x Substituting x=14x = 14: f(14)=42(14)=428=24f(14) = 4 - 2(14) = 4 - 28 = -24

Thus, f(g(3))=24f(g(-3)) = -24, which is correctly given.

Part b: gh(20)g \circ h(20) (This means g(h(20))g(h(20)))

  1. First, find h(20)h(20): h(x)=x67h(x) = \frac{x - 6}{7} Substituting x=20x = 20: h(20)=2067=147=2h(20) = \frac{20 - 6}{7} = \frac{14}{7} = 2

  2. Now, find g(2)g(2): g(x)=x2+5g(x) = x^2 + 5 Substituting x=2x = 2: g(2)=22+5=4+5=9g(2) = 2^2 + 5 = 4 + 5 = 9

Thus, gh(20)=9g \circ h(20) = 9.

Part c: h(f(g(3)))h(f(g(3)))

  1. First, find g(3)g(3): g(3)=32+5=9+5=14g(3) = 3^2 + 5 = 9 + 5 = 14

  2. Now, find f(14)f(14) (which we already computed in Part a): f(14)=24f(14) = -24

  3. Now, find h(24)h(-24): h(x)=x67h(x) = \frac{x - 6}{7} Substituting x=24x = -24: h(24)=2467=307h(-24) = \frac{-24 - 6}{7} = \frac{-30}{7}

Thus, h(f(g(3)))=307h(f(g(3))) = \frac{-30}{7}.

Final Answers:

a. f(g(3))=24f(g(-3)) = -24 (Given) b. gh(20)=9g \circ h(20) = 9 c. h(f(g(3)))=307h(f(g(3))) = \frac{-30}{7}

Would you like further details or explanations on any part of this?

Here are some related questions:

  1. How would you compute f(h(g(x)))f(h(g(x))) for an arbitrary xx?
  2. What would h(f(h(x)))h(f(h(x))) be for a general input xx?
  3. Can you find the composite function fg(x)f \circ g(x) for a general xx?
  4. What would the graph of h(x)h(x) look like, and how would its slope affect the composite functions?
  5. If g(x)g(x) were different, say g(x)=x25g(x) = x^2 - 5, how would that change the result for part c?

Tip: When dealing with composite functions, always evaluate the innermost function first before moving to the outer ones.

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Math Problem Analysis

Mathematical Concepts

Composite Functions
Function Evaluation
Algebra

Formulas

f(x) = 4 - 2x
g(x) = x^2 + 5
h(x) = (x - 6) / 7

Theorems

Composite Functions

Suitable Grade Level

High School (Grades 9-12)