Math Problem Statement

MCD 4490-Oral Presentation Tri2-2024 Week 12.pdf

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solve questions with detailed explanation. start with the functions

Solution

Let's begin with Question 1 from the "Functions and Graphs" section:


Problem:

You are given two functions:
f(x)=x1andg(x)=2x2f(x) = x - 1 \quad \text{and} \quad g(x) = \frac{2}{x-2}

  1. Find p(x)=(fg)(x)p(x) = (f \circ g)(x), and determine its domain.
  2. Find the inverse of p(x)p(x), and sketch the graphs of p(x)p(x) and p1(x)p^{-1}(x).

Solution:

1. Finding p(x)=f(g(x))p(x) = f(g(x)):

First, let's substitute g(x)g(x) into f(x)f(x): p(x)=f(g(x))=f(2x2)p(x) = f(g(x)) = f\left( \frac{2}{x-2} \right) Since f(x)=x1f(x) = x - 1, we replace the xx in f(x)f(x) with g(x)g(x): p(x)=(2x2)1p(x) = \left( \frac{2}{x-2} \right) - 1 Simplifying the expression: p(x)=2x21=2x2x2x2p(x) = \frac{2}{x-2} - 1 = \frac{2}{x-2} - \frac{x-2}{x-2} p(x)=2(x2)x2=2x+2x2=4xx2p(x) = \frac{2 - (x-2)}{x-2} = \frac{2 - x + 2}{x-2} = \frac{4 - x}{x-2} Thus, p(x)=4xx2p(x) = \frac{4 - x}{x-2}.


Domain of p(x)p(x):

  • The domain of g(x)g(x) is restricted by the fact that g(x)=2x2g(x) = \frac{2}{x-2} is undefined when x=2x = 2. Hence, x2x \neq 2.
  • The expression for p(x)=4xx2p(x) = \frac{4-x}{x-2} does not introduce any new restrictions, so the domain remains x2x \neq 2.

Thus, the domain of p(x)p(x) is:
x(,2)(2,)x \in (-\infty, 2) \cup (2, \infty)


2. Finding the inverse p1(x)p^{-1}(x):

We now solve for xx in terms of yy, where y=p(x)y = p(x): y=4xx2y = \frac{4 - x}{x - 2} Multiply both sides by (x2)(x-2) to eliminate the denominator: y(x2)=4xy(x - 2) = 4 - x Expanding both sides: yx2y=4xyx - 2y = 4 - x Rearranging the terms to isolate xx: yx+x=4+2yyx + x = 4 + 2y x(y+1)=4+2yx(y + 1) = 4 + 2y Solving for xx: x=4+2yy+1x = \frac{4 + 2y}{y + 1}

Thus, the inverse function is: p1(x)=4+2xx+1p^{-1}(x) = \frac{4 + 2x}{x + 1}


Graphing p(x)p(x) and p1(x)p^{-1}(x):

  1. Graph of p(x)=4xx2p(x) = \frac{4 - x}{x-2}:

    • Asymptote at x=2x = 2 (since p(x)p(x) is undefined at x=2x = 2).
    • Horizontal asymptote: As xx \to \infty, p(x)1p(x) \to -1, so there is a horizontal asymptote at y=1y = -1.
  2. Graph of p1(x)=4+2xx+1p^{-1}(x) = \frac{4 + 2x}{x + 1}:

    • Asymptote at x=1x = -1 (since p1(x)p^{-1}(x) is undefined at x=1x = -1).
    • Horizontal asymptote: As xx \to \infty, p1(x)2p^{-1}(x) \to 2, so there is a horizontal asymptote at y=2y = 2.

Both functions are reflected over the line y=xy = x.


Would you like more details on any part of the solution, or perhaps some assistance in visualizing the graphs?


Follow-up questions:

  1. How do you find the composite of two functions in general?
  2. What are the rules for determining the domain of a composite function?
  3. How can you verify if a function has an inverse?
  4. What is the relationship between the graphs of a function and its inverse?
  5. How do asymptotes help in sketching graphs of rational functions?

Tip:

When finding the inverse of a function, always verify by substituting the inverse into the original function to ensure it returns the identity function f(f1(x))=xf(f^{-1}(x)) = x.

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Math Problem Analysis

Mathematical Concepts

Functions
Graphing
Inverse Functions
Domain and Range

Formulas

f(x) = x - 1
g(x) = 2 / (x - 2)
p(x) = (f ∘ g)(x)
p⁻¹(x)

Theorems

Inverse Function Theorem
Composition of Functions
Asymptotes in Rational Functions

Suitable Grade Level

Grades 11-12 or first-year university level