26.23 problem 759

Internal problem ID [4000]

Book: Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section: Various 26
Problem number: 759.
ODE order: 1.
ODE degree: 2.

CAS Maple gives this as type [_quadrature]

\[ \boxed {{y^{\prime }}^{2}-y^{2} b=a} \]

Solution by Maple

Time used: 0.031 (sec). Leaf size: 114

dsolve(diff(y(x),x)^2 = a+b*y(x)^2,y(x), singsol=all)
 

\begin{align*} y \left (x \right ) = \frac {\sqrt {-a b}}{b} y \left (x \right ) = -\frac {\sqrt {-a b}}{b} y \left (x \right ) = \frac {\left ({\mathrm e}^{-2 c_{1} \sqrt {b}} {\mathrm e}^{2 x \sqrt {b}}-a \right ) {\mathrm e}^{c_{1} \sqrt {b}} {\mathrm e}^{-x \sqrt {b}}}{2 \sqrt {b}} y \left (x \right ) = \frac {\left ({\mathrm e}^{2 c_{1} \sqrt {b}} {\mathrm e}^{-2 x \sqrt {b}}-a \right ) {\mathrm e}^{-c_{1} \sqrt {b}} {\mathrm e}^{x \sqrt {b}}}{2 \sqrt {b}} \end{align*}

Solution by Mathematica

Time used: 60.109 (sec). Leaf size: 171

DSolve[(y'[x])^2==a+b y[x]^2,y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to -\frac {\sqrt {a} \tanh \left (\sqrt {b} (x-c_1)\right )}{\sqrt {b \text {sech}^2\left (\sqrt {b} (x-c_1)\right )}} y(x)\to \frac {\sqrt {a} \tanh \left (\sqrt {b} (x-c_1)\right )}{\sqrt {b \text {sech}^2\left (\sqrt {b} (x-c_1)\right )}} y(x)\to -\frac {\sqrt {a} \tanh \left (\sqrt {b} (x+c_1)\right )}{\sqrt {b \text {sech}^2\left (\sqrt {b} (x+c_1)\right )}} y(x)\to \frac {\sqrt {a} \tanh \left (\sqrt {b} (x+c_1)\right )}{\sqrt {b \text {sech}^2\left (\sqrt {b} (x+c_1)\right )}} \end{align*}