Math Problem Statement

Let f(x) = x^2 - 2 and g(x) = 3x - 2, evaluate the following: a) f(-2) b) f(-1) + g(-2) c) 3f(x) + g(x) d) f(g(4)) e) g(f(4))

Solution

Let's go through each of the sub-problems step by step.

We are given two functions: f(x)=x22andg(x)=3x2f(x) = x^2 - 2 \quad \text{and} \quad g(x) = 3x - 2

Part a: f(2)f(-2)

We substitute x=2x = -2 into the function f(x)f(x):

f(2)=(2)22=42=2f(-2) = (-2)^2 - 2 = 4 - 2 = 2

Thus, f(2)=2f(-2) = 2.

Part b: f(1)+g(2)f(-1) + g(-2)

  1. First, calculate f(1)f(-1): f(1)=(1)22=12=1f(-1) = (-1)^2 - 2 = 1 - 2 = -1

  2. Now, calculate g(2)g(-2): g(2)=3(2)2=62=8g(-2) = 3(-2) - 2 = -6 - 2 = -8

Now, add the two results: f(1)+g(2)=1+(8)=9f(-1) + g(-2) = -1 + (-8) = -9

Thus, f(1)+g(2)=9f(-1) + g(-2) = -9.

Part c: 3f(x)+g(x)3f(x) + g(x)

We substitute the expressions for f(x)f(x) and g(x)g(x):

3f(x)+g(x)=3(x22)+(3x2)3f(x) + g(x) = 3(x^2 - 2) + (3x - 2)

Now, expand and simplify:

3f(x)+g(x)=3x26+3x2=3x2+3x83f(x) + g(x) = 3x^2 - 6 + 3x - 2 = 3x^2 + 3x - 8

Thus, 3f(x)+g(x)=3x2+3x83f(x) + g(x) = 3x^2 + 3x - 8.

Part d: f(g(4))f(g(4))

  1. First, calculate g(4)g(4): g(4)=3(4)2=122=10g(4) = 3(4) - 2 = 12 - 2 = 10

  2. Now, substitute this result into f(x)f(x): f(10)=(10)22=1002=98f(10) = (10)^2 - 2 = 100 - 2 = 98

Thus, f(g(4))=98f(g(4)) = 98.

Part e: g(f(4))g(f(4))

  1. First, calculate f(4)f(4): f(4)=(4)22=162=14f(4) = (4)^2 - 2 = 16 - 2 = 14

  2. Now, substitute this result into g(x)g(x): g(14)=3(14)2=422=40g(14) = 3(14) - 2 = 42 - 2 = 40

Thus, g(f(4))=40g(f(4)) = 40.

Final Answers:

  • a. f(2)=2f(-2) = 2
  • b. f(1)+g(2)=9f(-1) + g(-2) = -9
  • c. 3f(x)+g(x)=3x2+3x83f(x) + g(x) = 3x^2 + 3x - 8
  • d. f(g(4))=98f(g(4)) = 98
  • e. g(f(4))=40g(f(4)) = 40

Would you like any further details or explanations?


Here are five related questions for further practice:

  1. What is f(g(1))f(g(-1))?
  2. Find the value of g(f(3))g(f(3)).
  3. Simplify 2f(x)+g(x)2f(x) + g(x).
  4. What is f(x)+g(x)f(x) + g(x) in general form?
  5. Calculate f(g(0))f(g(0)).

Tip: When evaluating composite functions, always start from the inside and work outward!

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions
Composite Functions

Formulas

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

Theorems

Function Evaluation

Suitable Grade Level

Grades 9-11