Skip to main content
Ch. 5 - Systems of Equations and Inequalities
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Non è quello che usi tu?Cambia libro di testo
Capitolo 6, Problema 39

Write the partial fraction decomposition of each rational expression. (x3-4x2+9x-5)/(x2 -2x+3)2

Guida verificata passo dopo passo
1
Identify the denominator and its factors. Here, the denominator is \( (x^{2} - 2x + 3)^{2} \), which is a repeated irreducible quadratic factor since \( x^{2} - 2x + 3 \) cannot be factored further over the reals.
Set up the form of the partial fraction decomposition. For a repeated irreducible quadratic factor \( (ax^{2} + bx + c)^{2} \), the decomposition includes terms with linear numerators over each power of the quadratic factor. So, write:
\[ \frac{x^{3} - 4x^{2} + 9x - 5}{(x^{2} - 2x + 3)^{2}} = \frac{Ax + B}{x^{2} - 2x + 3} + \frac{Cx + D}{(x^{2} - 2x + 3)^{2}} \]
Multiply both sides of the equation by the denominator \( (x^{2} - 2x + 3)^{2} \) to clear the fractions:
\[ x^{3} - 4x^{2} + 9x - 5 = (Ax + B)(x^{2} - 2x + 3) + (Cx + D) \]
Expand the right-hand side and then collect like terms by powers of \( x \). This will give you a polynomial equation where the coefficients of corresponding powers of \( x \) on both sides must be equal. From this, you can set up a system of equations to solve for \( A, B, C, \) and \( D \).

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
9m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Partial Fraction Decomposition

Partial fraction decomposition is a method used to express a rational function as a sum of simpler fractions, making integration or other operations easier. It involves breaking down a complex rational expression into a sum of fractions with simpler denominators, typically linear or quadratic factors.
Video consigliato:
4:07
Decomposition of Functions

Repeated Quadratic Factors in Denominators

When the denominator contains a repeated irreducible quadratic factor, such as (x² - 2x + 3)², the decomposition includes terms with the quadratic factor raised to increasing powers. Each term has a numerator that is a linear polynomial, reflecting the irreducible quadratic nature.
Video consigliato:
02:58
Rationalizing Denominators

Degree Comparison Between Numerator and Denominator

Before decomposing, ensure the degree of the numerator is less than the degree of the denominator. If not, perform polynomial division first. In this problem, the numerator is degree 3 and the denominator degree 4, so decomposition can proceed directly.
Video consigliato:
02:58
Rationalizing Denominators