82.8.10 problem 36-11

Internal problem ID [21881]
Book : The Differential Equations Problem Solver. VOL. II. M. Fogiel director. REA, NY. 1978. ISBN 78-63609
Section : Chapter 36. Nonlinear differential equations. Page 1203
Problem number : 36-11
Date solved : Thursday, October 02, 2025 at 08:03:26 PM
CAS classification : [[_2nd_order, _missing_x], [_2nd_order, _exact, _nonlinear], [_2nd_order, _reducible, _mu_x_y1], [_2nd_order, _reducible, _mu_xy]]

\begin{align*} 1+{y^{\prime }}^{2}+y y^{\prime \prime }&=0 \end{align*}

✓ Maple. Time used: 0.010 (sec). Leaf size: 39

ode:=y(x)*diff(diff(y(x),x),x)+diff(y(x),x)^2+1 = 0; 
dsolve(ode,y(x), singsol=all);
 

\begin{align*} y &= \sqrt {-2 c_1 x -x^{2}+2 c_2} \\ y &= -\sqrt {-2 c_1 x -x^{2}+2 c_2} \\ \end{align*}

✓ Mathematica. Time used: 8.105 (sec). Leaf size: 83

ode=y[x]*D[y[x],{x,2}]+D[y[x],x]^2+1==0; 
ic={}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 

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

✗ Sympy

from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(y(x)*Derivative(y(x), (x, 2)) + Derivative(y(x), x)**2 + 1,0) 
ics = {} 
dsolve(ode,func=y(x),ics=ics)
 

NotImplementedError : The given ODE -sqrt(-y(x)*Derivative(y(x), (x, 2)) - 1) + Derivative(y(x), x) cannot be solved by the factorable group method