71.8.43 problem 14 (c)

Internal problem ID [14406]
Book : Ordinary Differential Equations by Charles E. Roberts, Jr. CRC Press. 2010
Section : Chapter 2. The Initial Value Problem. Exercises 2.4.4, page 115
Problem number : 14 (c)
Date solved : Monday, March 31, 2025 at 12:26:07 PM
CAS classification : [[_1st_order, _with_linear_symmetries], _Clairaut]

\begin{align*} y^{\prime }&=-\frac {x}{2}+\frac {\sqrt {x^{2}+4 y}}{2} \end{align*}

With initial conditions

\begin{align*} y \left (0\right )&=-1 \end{align*}

✓ Maple. Time used: 0.464 (sec). Leaf size: 17

ode:=diff(y(x),x) = -1/2*x+1/2*(x^2+4*y(x))^(1/2); 
ic:=y(0) = -1; 
dsolve([ode,ic],y(x), singsol=all);
 

\begin{align*} y &= -i x -1 \\ y &= i x -1 \\ \end{align*}

✓ Mathematica. Time used: 0.494 (sec). Leaf size: 23

ode=D[y[x],x]==(-x+Sqrt[x^2+4*y[x]])/2; 
ic={y[0]==-1}; 
DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
 

\begin{align*} y(x)\to -1-i x \\ y(x)\to -1+i x \\ \end{align*}

✗ Sympy

from sympy import * 
x = symbols("x") 
y = Function("y") 
ode = Eq(x/2 - sqrt(x**2 + 4*y(x))/2 + Derivative(y(x), x),0) 
ics = {y(0): -1} 
dsolve(ode,func=y(x),ics=ics)
 

NotImplementedError : Initial conditions produced too many solutions for constants