\[ a y'(x)^2+y(x) y'(x)-x=0 \] ✓ Mathematica : cpu = 1.11934 (sec), leaf count = 61
\[\text {Solve}\left [\left \{x=\frac {a K[1] \sin ^{-1}(K[1])}{\sqrt {1-K[1]^2}}+\frac {c_1 K[1]}{\sqrt {1-K[1]^2}},y(x)=\frac {x}{K[1]}-a K[1]\right \},\{y(x),K[1]\}\right ]\] ✓ Maple : cpu = 0.201 (sec), leaf count = 378
\[\frac {c_{1} \left (y \relax (x )-\sqrt {4 a x +y \relax (x )^{2}}\right )}{\sqrt {\frac {-y \relax (x )+\sqrt {4 a x +y \relax (x )^{2}}+2 a}{a}}\, \sqrt {\frac {-y \relax (x )+\sqrt {4 a x +y \relax (x )^{2}}-2 a}{a}}}+x +\frac {\left (-y \relax (x )+\sqrt {4 a x +y \relax (x )^{2}}\right ) \ln \left (\frac {\sqrt {\frac {4 a x +2 y \relax (x )^{2}-2 y \relax (x ) \sqrt {4 a x +y \relax (x )^{2}}-4 a^{2}}{a^{2}}}\, a +\sqrt {4 a x +y \relax (x )^{2}}-y \relax (x )}{2 a}\right )}{\sqrt {-\frac {2 \left (y \relax (x ) \sqrt {4 a x +y \relax (x )^{2}}+2 a^{2}-2 a x -y \relax (x )^{2}\right )}{a^{2}}}} = 0\]