Chapter 11: Problem 19
\(13-44=\) Find the partial fraction decomposition of the rational function. $$ \frac{4}{x^{2}-4} $$
Short Answer
Expert verified
The partial fraction decomposition is \(\frac{1}{x-2} - \frac{1}{x+2}\).
Step by step solution
01
Identify Denominator
The denominator of the rational function is \(x^2 - 4\), which can be factored using the difference of squares formula: \(x^2 - 4 = (x-2)(x+2)\).
02
Set Up Partial Fractions
Using the factors from the denominator, express the rational function as a sum of partial fractions: \(\frac{4}{x^2 - 4} = \frac{A}{x-2} + \frac{B}{x+2}\), where \(A\) and \(B\) are constants to be determined.
03
Combine Fractions
Combine the partial fractions on the right-hand side: \(\frac{A}{x-2} + \frac{B}{x+2} = \frac{A(x+2) + B(x-2)}{(x-2)(x+2)}\).
04
Set Equal and Solve for Coefficients
Since the denominators are the same, set the numerators equal: \[ 4 = A(x+2) + B(x-2) \]Expand and equate coefficients:\[ 4 = Ax + 2A + Bx - 2B \]Combine like terms:\[ 4 = (A + B)x + (2A - 2B) \]This gives us the system:\( A + B = 0 \)\( 2A - 2B = 4 \).
05
Solve the System of Equations
Use the system of equations to find \(A\) and \(B\):1. \(A + B = 0\) implies \(B = -A\).2. Substitute \(B = -A\) into \(2A - 2B = 4\): \[ 2A - 2(-A) = 4 \] \[ 2A + 2A = 4 \] \[ 4A = 4 \] \[ A = 1 \]3. Since \(B = -A\), then \(B = -1\).
06
Write Final Partial Fraction Decomposition
Substitute the values of \(A\) and \(B\) back into the partial fraction form:\[ \frac{4}{x^2 - 4} = \frac{1}{x-2} - \frac{1}{x+2} \].
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
The concept of the **Difference of Squares** is a key algebraic identity used in simplifying expressions, especially in decomposition of fractions. In our given example, the expression in the denominator is \( x^2 - 4 \). This can be rewritten as a product using the difference of squares formula:
- Formula: \( a^2 - b^2 = (a - b)(a + b) \)
- Application: For \( x^2 - 4 \), consider \( a = x \) and \( b = 2 \), so \( x^2 - 4 = (x - 2)(x + 2) \)
Rational Functions
A **Rational Function** is a ratio of two polynomials. In this exercise, we work with the rational function \( \frac{4}{x^2 - 4} \). Understanding rational functions is important since they're common in calculus and algebra, helping to describe various real-world scenarios.
- Numerator: The polynomial at the top, which in this case is 4.
- Denominator: The polynomial at the bottom, \( x^2 - 4 \), which we've already factored.
Algebraic Manipulation
Algebraic manipulation involves systematically rewriting expressions to simplify or solve equations. Here, it played a crucial role in the partial fraction decomposition process.
- Identify: Recognize how to break down the denominator into factors using the difference of squares.
- Set Up: Express the fraction as a sum of simpler fractions: \( \frac{A}{x-2} + \frac{B}{x+2} \).
- Combine: Merge these fractions, focusing on the numerator, resulting in \( A(x + 2) + B(x - 2) \).
- Solve: Equate the numerator from this combined fraction to the original, \( 4 = A(x + 2) + B(x - 2) \), and solve the resulting system of equations.