\[ x^2 y''(x)-\sqrt {a x^2 y'(x)^2+b y(x)^2}=0 \] ✗ Mathematica : cpu = 1.57424 (sec), leaf count = 0 , could not solve
DSolve[-Sqrt[b*y[x]^2 + a*x^2*Derivative[1][y][x]^2] + x^2*Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 0.289 (sec), leaf count = 60
\[ \left \{ y \left ( x \right ) -{{\rm e}^{\int ^{\ln \left ( x \right ) }\!{\it RootOf} \left ( \int ^{{\it \_Z}}\!-{y \left ( x \right ) \left ( {{\it \_a}}^{2}y \left ( x \right ) -{\it \_a}\,y \left ( x \right ) -\sqrt { \left ( y \left ( x \right ) \right ) ^{2} \left ( {{\it \_a}}^{2}a+b \right ) } \right ) ^{-1}}{d{\it \_a}}-{\it \_b}+{\it \_C1} \right ) {d{\it \_b}}+{\it \_C2}}}=0 \right \} \]