Differential Equations and Linear Algebra (4th Edition)

Published by Pearson
ISBN 10: 0-32196-467-5
ISBN 13: 978-0-32196-467-0

Chapter 8 - Linear Differential Equations of Order n - 8.9 Reduction of Order - Problems - Page 572: 1

Answer

See below

Work Step by Step

Given $x^2y''-3xy'+4y=0$ We first compute the appropriate derivatives: $y'=x^2(u'+u)\\ y''=x^2(u''+u'+u)$ Substitute: $x^4(u''+u'+u)-3x^3(u'+u)+4x^2u=0$ which simplifies to $x^4u''+x^3u'=0$ or equivalently, $w'x+w=0$ where $w=u'$ Separating the variables yields $-x=\frac{w}{w'}$ By integrating, we obtain $\ln w=-\ln x +C\\ wx=k$ Therefore, $u'=\frac{k}{x}$ Integration by parts gives $u=k\ln x +C$ The general solution is $y=C_1x^2+C_2x^2 \ln x$
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