23.4.135 problem 135

Internal problem ID [6437]
Book : Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section : Part II. Chapter 4. THE NONLINEAR EQUATION OF SECOND ORDER, page 380
Problem number : 135
Date solved : Tuesday, September 30, 2025 at 02:56:50 PM
CAS classification : [[_2nd_order, _missing_x], [_2nd_order, _reducible, _mu_xy]]

\begin{align*} y y^{\prime \prime }&=\ln \left (y\right ) y^{2}+{y^{\prime }}^{2} \end{align*}

✓ Maple. Time used: 0.018 (sec). Leaf size: 18

ode:=y(x)*diff(diff(y(x),x),x) = ln(y(x))*y(x)^2+diff(y(x),x)^2; 
dsolve(ode,y(x), singsol=all);
 

\[ y = {\mathrm e}^{\frac {c_1 \,{\mathrm e}^{-x}}{2}-\frac {c_2 \,{\mathrm e}^{x}}{2}} \]

✓ Mathematica. Time used: 0.59 (sec). Leaf size: 63

ode=y[x]*D[y[x],{x,2}] == Log[y[x]]*y[x]^2 + D[y[x],x]^2; 
ic={}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 

\begin{align*} y(x)&\to e^{\frac {1}{2} \left (e^{x+c_2}-c_1 e^{-x-c_2}\right )}\\ y(x)&\to e^{\frac {1}{2} \left (e^{-x-c_2}-c_1 e^{x+c_2}\right )} \end{align*}

✗ Sympy

from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(-y(x)**2*log(y(x)) + y(x)*Derivative(y(x), (x, 2)) - Derivative(y(x), x)**2,0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics)
 

TypeError : cannot determine truth value of Relational: _X0**2 < 2