Math Problem Statement

Find the values of f(5), g(8), and 2f(5) - g(8) given the piecewise functions f(x) and g(x).

Solution

Let's break down the given piecewise functions f(x)f(x) and g(x)g(x) and then solve the required values.

Function f(x)f(x):

  • f(x)=x2+5f(x) = x^2 + 5, when x2x \leq 2
  • f(x)=3xf(x) = -3x, when x>2x > 2

Function g(x)g(x):

  • g(x)=5x+7g(x) = 5x + 7, when x<0x < 0
  • g(x)=(x1)2+2g(x) = (x - 1)^2 + 2, when 0x<40 \leq x < 4
  • g(x)=xg(x) = -x, when x4x \geq 4

1. Finding f(5)f(5):

Since 5>25 > 2, we use the second piece of f(x)f(x): f(5)=3(5)=15f(5) = -3(5) = -15

2. Finding g(8)g(8):

Since 848 \geq 4, we use the third piece of g(x)g(x): g(8)=8g(8) = -8

3. Finding 2f(5)g(8)2f(5) - g(8):

First, we compute 2f(5)2f(5): 2f(5)=2(15)=302f(5) = 2(-15) = -30 Now, subtract g(8)g(8) from 2f(5)2f(5): 2f(5)g(8)=30(8)=30+8=222f(5) - g(8) = -30 - (-8) = -30 + 8 = -22

Final Answers:

  • f(5)=15f(5) = -15
  • g(8)=8g(8) = -8
  • 2f(5)g(8)=222f(5) - g(8) = -22

Would you like further details or clarification on any step?

Here are 5 questions that build on this:

  1. How would the value of f(x)f(x) change if xx were a negative number?
  2. What would g(0)g(0) be based on the piecewise definition of g(x)g(x)?
  3. How do piecewise functions model different behaviors of real-world systems?
  4. How does the domain restriction affect which part of the function is applied?
  5. What is the difference between evaluating a continuous function versus a piecewise function?

Tip: Always check the domain before plugging in values in a piecewise function to ensure you're using the correct expression!

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Math Problem Analysis

Mathematical Concepts

Piecewise Functions
Algebra

Formulas

f(x) = x^2 + 5 for x <= 2
f(x) = -3x for x > 2
g(x) = 5x + 7 for x < 0
g(x) = (x - 1)^2 + 2 for 0 <= x < 4
g(x) = -x for x >= 4

Theorems

Piecewise function evaluation based on domain

Suitable Grade Level

Grade 9-12