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 - 8.7 The Variation of Parameters Method - Problems - Page 556: 25

Answer

See below

Work Step by Step

Given: $y''+y'-2y=F(x)$ Two linearly independent solutions to the associated homogeneous differential equation are: $y_1(x)=e^{-2x}\\ y_2(x)=e^{x}$ 2 with Wronskian $W_{y_1,y_2}(x)=(e^{-2x})(e^{x})-(-2e^{-2x})(e^{x})=3e^{-x}$ Obtain: $K(x,t)=\frac{1}{3}(e^{-2t}e^{x}-e^{t}e^{-x})$ Consequently: $y_p(x)=\frac{1}{3} \int^x_{x_0} (e^{2x-2t}-e^{t-x} F(t)dt$ The general solution to the given differential equation can therefore be expressed as $y(x)=c_1e^{-2x}+c_2e^{x}+\frac{1}{3} \int^x_{x_0} (e^{2x-2t}-e^{t-x} F(t)dt$
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