Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - Chapter 9 Test Prep - 955 - Page 955: 52

Answer

$\dfrac{x^3+2x^2-3}{(x^2-2)^2}=\dfrac{x+2}{x^2-2}+\dfrac{2x+1}{(x^2-2)^2}$

Work Step by Step

We will write the partial decomposition as: $\dfrac{x^3+2x^2-3}{(x^2-2)^2}=\dfrac{Ax+B}{x^2-2}+\dfrac{Cx+D}{(x^2-2)^2} ~~~~(a)$ This implies that $x^3+2x^2-3=(Ax+B)(x^2-2)+(Cx+D) ~~~(b)$ On comparing coefficients, we get $A=1$ and $B=2$ Now, plug $A=1$ and $B=2$ in equation (b) to obtain: $C=2$ and $D=1$ Back substitution $A=1; C=-3$ and $x=-1$ in equation (b). So, the equation (a) becomes: $\dfrac{x^3+2x^2-3}{(x^2-2)^2}=\dfrac{x+2}{x^2-2}+\dfrac{2x+1}{(x^2-2)^2}$
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