27.2 problem 767

Internal problem ID [3500]

Book: Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section: Various 27
Problem number: 767.
ODE order: 1.
ODE degree: 2.

CAS Maple gives this as type [[_1st_order, _with_symmetry_[F(x),G(x)*y+H(x)]]]

Solve \begin {gather*} \boxed {\left (y^{\prime }\right )^{2}+f \relax (x ) \left (y-a \right ) \left (y-b \right ) \left (y-c \right )=0} \end {gather*}

Solution by Maple

Time used: 0.109 (sec). Leaf size: 158

dsolve(diff(y(x),x)^2+f(x)*(y(x)-a)*(y(x)-b)*(y(x)-c) = 0,y(x), singsol=all)
 

\begin{align*} \int _{}^{y \relax (x )}\frac {1}{\sqrt {-\left (-\textit {\_a} +c \right ) \left (-\textit {\_a} +b \right ) \left (-\textit {\_a} +a \right )}}d \textit {\_a} +\int _{}^{x}-\frac {\sqrt {f \left (\textit {\_a} \right ) \left (-y \relax (x )+c \right ) \left (-y \relax (x )+b \right ) \left (-y \relax (x )+a \right )}}{\sqrt {-\left (-y \relax (x )+c \right ) \left (-y \relax (x )+b \right ) \left (-y \relax (x )+a \right )}}d \textit {\_a} +c_{1} = 0 \\ \int _{}^{y \relax (x )}\frac {1}{\sqrt {-\left (-\textit {\_a} +c \right ) \left (-\textit {\_a} +b \right ) \left (-\textit {\_a} +a \right )}}d \textit {\_a} +\int _{}^{x}\frac {\sqrt {f \left (\textit {\_a} \right ) \left (-y \relax (x )+c \right ) \left (-y \relax (x )+b \right ) \left (-y \relax (x )+a \right )}}{\sqrt {-\left (-y \relax (x )+c \right ) \left (-y \relax (x )+b \right ) \left (-y \relax (x )+a \right )}}d \textit {\_a} +c_{1} = 0 \\ \end{align*}

Solution by Mathematica

Time used: 60.303 (sec). Leaf size: 213

DSolve[(y'[x])^2+f[x](y[x]-a)(y[x]-b)(y[x]-c)==0,y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to \text {ns}\left (\frac {1}{2} \sqrt {a-b} \left (c_1+\int _1^x-\sqrt {f(K[1])}dK[1]\right )|\frac {a-c}{a-b}\right ){}^2 \left (a \text {sn}\left (\frac {1}{2} \sqrt {a-b} \left (c_1+\int _1^x-\sqrt {f(K[1])}dK[1]\right )|\frac {a-c}{a-b}\right ){}^2-a+b\right ) \\ y(x)\to \text {ns}\left (\frac {1}{2} \sqrt {a-b} \left (c_1+\int _1^x\sqrt {f(K[2])}dK[2]\right )|\frac {a-c}{a-b}\right ){}^2 \left (a \text {sn}\left (\frac {1}{2} \sqrt {a-b} \left (c_1+\int _1^x\sqrt {f(K[2])}dK[2]\right )|\frac {a-c}{a-b}\right ){}^2-a+b\right ) \\ \end{align*}