Math Problem Statement

Given f(x) = (x+3)/(2x-7), g(x) = (2x-3)/(x+1), h(x) = (5x+1)/(3x-1), evaluate f(5) and g(4) and show that h(f(5)) = 43/21. Also, given f(x) = 3x-1, g(x) = 2x, and h(x) = x+1, find h(g(f(x))) and h(g(f(-2))).

Solution

Let's break down the tasks from your image step by step:

Question 8:

Given:

  • f(x)=x+32x7f(x) = \frac{x+3}{2x-7}
  • g(x)=2x3x+1g(x) = \frac{2x-3}{x+1}
  • h(x)=5x+13x1h(x) = \frac{5x+1}{3x-1}

You are asked to:

  1. Evaluate:
    • f(5)f(5)
    • g(4)g(4)
  2. Show that:
    • h(f(5))=4321h(f(5)) = \frac{43}{21}

Solution:

(a) Evaluate f(5)f(5) and g(4)g(4):

  1. For f(5)f(5): f(x)=x+32x7f(x) = \frac{x+3}{2x-7} Substitute x=5x = 5: f(5)=5+32(5)7=8107=83f(5) = \frac{5 + 3}{2(5) - 7} = \frac{8}{10 - 7} = \frac{8}{3}

  2. For g(4)g(4): g(x)=2x3x+1g(x) = \frac{2x - 3}{x + 1} Substitute x=4x = 4: g(4)=2(4)34+1=835=55=1g(4) = \frac{2(4) - 3}{4 + 1} = \frac{8 - 3}{5} = \frac{5}{5} = 1

(b) Show that h(f(5))=4321h(f(5)) = \frac{43}{21}:

  • First, recall that f(5)=83f(5) = \frac{8}{3}.
  • Now, substitute f(5)f(5) into the function h(x)h(x): h(x)=5x+13x1h(x) = \frac{5x+1}{3x-1} Substitute x=83x = \frac{8}{3} into h(x)h(x): h(83)=5(83)+13(83)1=403+181=403+337=4337h\left(\frac{8}{3}\right) = \frac{5\left(\frac{8}{3}\right) + 1}{3\left(\frac{8}{3}\right) - 1} = \frac{\frac{40}{3} + 1}{8 - 1} = \frac{\frac{40}{3} + \frac{3}{3}}{7} = \frac{\frac{43}{3}}{7} Simplifying further: h(83)=4321h\left(\frac{8}{3}\right) = \frac{43}{21} Thus, it is shown that h(f(5))=4321h(f(5)) = \frac{43}{21}.

Question 17:

Given:

  • f(x)=3x1f(x) = 3x - 1
  • g(x)=2xg(x) = 2x
  • h(x)=x+1h(x) = x + 1

You are asked to:

  1. Find h(g(f(x)))h(g(f(x)))
  2. Find h(g(f(2)))h(g(f(-2)))

Solution:

(a) Find h(g(f(x)))h(g(f(x))):

  1. First, find f(x)f(x): f(x)=3x1f(x) = 3x - 1
  2. Now, find g(f(x))g(f(x)): g(x)=2xsog(f(x))=2(3x1)=6x2g(x) = 2x \quad \text{so} \quad g(f(x)) = 2(3x - 1) = 6x - 2
  3. Finally, find h(g(f(x)))h(g(f(x))): h(x)=x+1soh(g(f(x)))=(6x2)+1=6x1h(x) = x + 1 \quad \text{so} \quad h(g(f(x))) = (6x - 2) + 1 = 6x - 1

(b) Find h(g(f(2)))h(g(f(-2))):

  1. First, calculate f(2)f(-2): f(2)=3(2)1=61=7f(-2) = 3(-2) - 1 = -6 - 1 = -7
  2. Now, calculate g(f(2))g(f(-2)): g(7)=2(7)=14g(-7) = 2(-7) = -14
  3. Finally, calculate h(g(f(2)))h(g(f(-2))): h(14)=14+1=13h(-14) = -14 + 1 = -13

Would you like to dive deeper into any part of the explanation, or do you have any questions?

Related Questions:

  1. How would the result change if f(x)f(x), g(x)g(x), or h(x)h(x) were modified?
  2. Can you evaluate h(g(f(1)))h(g(f(1))) using the same method?
  3. How would you approach finding g(h(f(x)))g(h(f(x)))?
  4. What happens to the compositions if the domain of one function is restricted?
  5. Can you derive the inverse of f(x)f(x) or g(x)g(x)?

Tip:

When working with composite functions, always start from the innermost function and work your way outward step by step.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebraic Manipulation
Rational Functions

Formulas

f(x) = (x+3)/(2x-7)
g(x) = (2x-3)/(x+1)
h(x) = (5x+1)/(3x-1)
f(x) = 3x-1
g(x) = 2x
h(x) = x+1

Theorems

Function Evaluation
Composition of Functions

Suitable Grade Level

Grades 10-12