Precalculus (6th Edition)

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

Chapter 9 - Systems and Matrices - 9.4 Partial Fractions - 9.4 Exercises - Page 895: 17

Answer

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

Work Step by Step

We will write the partial decomposition as: $\dfrac{2x+1}{(x+2)^3}=\dfrac{A}{x+2}+\dfrac{B}{(x+2)^2}+\dfrac{C}{(x+2)^3} ~~~~(a)$ This implies that $2x+1=A(x+2)^2+B(x+2)+C$ Plug $x=-3,0$ to obtain: $A -B=-2$ and $2A+B=2$ After solving these equations, we get: $A=0$ and $B=2$ Now, plug $x=-2$ to obtain: $C=-3$ So, the equation (a) becomes: $\dfrac{2x+1}{(x+2)^3}=\dfrac{2}{(x+2)^2}-\dfrac{3}{(x+2)^3}$
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