2.1811   ODE No. 1811

\[ \sqrt {x^2+y(x)^2} y''(x)-a \left (y'(x)^2+1\right )^{3/2}=0 \]

✗ Mathematica : cpu = 300.062 (sec), leaf count = 0

DSolve[-(a*(1 + Derivative[1][y][x]^2)^(3/2)) + Sqrt[x^2 + y[x]^2]*Derivative[2][y][x] == 0,y[x],x]
 

, timed out

$Aborted

✓ Maple : cpu = 2.12 (sec), leaf count = 88

dsolve((y(x)^2+x^2)^(1/2)*diff(diff(y(x),x),x)-a*(diff(y(x),x)^2+1)^(3/2)=0,y(x))
 

\[y \left (x \right ) = -i x\]