Elementary Differential Equations and Boundary Value Problems 9th Edition

Published by Wiley
ISBN 10: 0-47038-334-8
ISBN 13: 978-0-47038-334-6

Chapter 4 - Higher Order Linear Equations - 4.4 The Method of Variation of Parameters - Problems - Page 242: 13

Answer

$y_{p}=\frac{1}{15}x^4$

Work Step by Step

${y}'''+\frac{1}{x}{y}''-\frac{2}{x^2}{y}'+\frac{2}{x^3}y=2x$ $W(x,x^2,\frac{1}{x})=\begin{vmatrix} x & x^2 & \frac{1}{x} \\ 1 & 2x & -\frac{1}{x^2} \\ 0 & 2 & \frac{2}{x^3} \\ \end{vmatrix}\;=\;\frac{6}{x}$ $W_{1}=\begin{vmatrix} 0 & x^2 & \frac{1}{x} \\ 0 & 2x & -\frac{1}{x^2} \\ 2x & 2 & \frac{2}{x^3} \\ \end{vmatrix}\;=\;-6x$ $W_{2}=\begin{vmatrix} x & 0 & \frac{1}{x} \\ 1 & 0 & -\frac{1}{x^2} \\ 0 & 2x & \frac{2}{x^3} \\ \end{vmatrix}\;=\;4$ $W_{3}=\begin{vmatrix} x & x^2 & 0 \\ 1 & 2x & 0 \\ 0 & 2 & 2x \\ \end{vmatrix}\;=\;2x^3$ ${u}'_{1}=\frac{w_{1}}{w}=-x^2$ $u_{1}=\int -x^2=-\frac{1}{3}x^3$ ${u}'_{2}=\frac{w_{2}}{w}=\frac{2}{3}x$ $u_{2}=\int \frac{2}{3}x= \frac{1}{3} x^3$ ${u}'_{3}=\frac{w_{3}}{w}=\frac{1}{3}x^4$ $u_{3}=\int \frac{1}{3}x^4= \frac{1}{15} x^5 $ $y_{p}=y_{1}u_{1}+y_{2}u_{2}+y_{3}u_{3}$ $y_{p}=-\frac{1}{3}x^4+\frac{1}{3}x^4+\frac{1}{15}x^4=\frac{1}{15}x^4$ $y_{p}=\frac{1}{15}x^4$
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