29.15.21 problem 429

Internal problem ID [5027]
Book : Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section : Various 15
Problem number : 429
Date solved : Tuesday, March 04, 2025 at 07:44:13 PM
CAS classification : [_quadrature]

\begin{align*} y y^{\prime }&=\sqrt {y^{2}+a^{2}} \end{align*}

✓ Maple. Time used: 0.001 (sec). Leaf size: 18

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

\[ x -\sqrt {a^{2}+y \left (x \right )^{2}}+c_{1} = 0 \]

✓ Mathematica. Time used: 0.233 (sec). Leaf size: 61

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

\begin{align*} y(x)\to -\sqrt {-a^2+(x+c_1){}^2} \\ y(x)\to \sqrt {-a^2+(x+c_1){}^2} \\ y(x)\to -i a \\ y(x)\to i a \\ \end{align*}

✓ Sympy. Time used: 0.973 (sec). Leaf size: 42

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

\[ \left [ y{\left (x \right )} = - \sqrt {C_{1}^{2} + 2 C_{1} x - a^{2} + x^{2}}, \ y{\left (x \right )} = \sqrt {C_{1}^{2} + 2 C_{1} x - a^{2} + x^{2}}\right ] \]