Differential Equations and Linear Algebra (4th Edition)

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

Chapter 1 - First-Order Differential Equations - 1.4 Separable Differential Equations - Problems - Page 43: 16

Answer

See below

Work Step by Step

Given: $\frac{dy}{dx}=\frac{2}{3}(y-1)^{1/2}\\ \Leftrightarrow\frac{dy}{dx}\frac{1}{\sqrt y-1}=\frac{2}{3}$ Integrate: $\int \frac{1}{\sqrt y-1}dy=\int \frac{2}{3}dx\\ \rightarrow 2\sqrt y-1=\frac{2}{3}x+c\\ \rightarrow \sqrt y-1=\frac{1}{3}x+\frac{1}{2}c\\ \rightarrow \sqrt y-1-\frac{1}{3}x=\frac{1}{2}c$ Substitute: $\rightarrow \sqrt 1-1-\frac{1}{3}(1)=\frac{1}{2}c\\ \rightarrow c=-\frac{1}{3}$ then $\sqrt y-1=\frac{1}{3}x-\frac{1}{3}\\ \rightarrow \sqrt y-1=\frac{x-1}{3}\\ \rightarrow y-1=(\frac{x-1}{3})^2\\ \rightarrow y-1=\frac{x^2-2x+1}{9}\\ \rightarrow y=\frac{x^2-2x+10}{9}$ We can see that the equation has more than one solution at $y=1$, then this equation is an exception to the Uniqueness and Existence Theorem.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.