\[ \left (a+x y'(x)\right )^2-2 a y(x)+x^2=0 \] ✓ Mathematica : cpu = 1.83313 (sec), leaf count = 49
\[\text {Solve}\left [\left \{\frac {\left (\text {K$\$$3172799}^2+1\right ) x^2}{a}+a+2 \text {K$\$$3172799} x=2 y(x),x=\frac {c_1-a \sinh ^{-1}(\text {K$\$$3172799})}{\sqrt {\text {K$\$$3172799}^2+1}}\right \},\{y(x),\text {K$\$$3172799}\}\right ]\]
✓ Maple : cpu = 9.984 (sec), leaf count = 242
\[ \left \{ y \left ( x \right ) ={\frac {1}{2\,a \left ( \left ( {\it RootOf} \left ( \left ( {\it Arcsinh} \left ( {\it \_Z} \right ) \right ) ^{2}{a}^{2}-{{\it \_Z}}^{2}{x}^{2}-2\,{\it Arcsinh} \left ( {\it \_Z} \right ) {\it \_C1}\,a+{{\it \_C1}}^{2}-{x}^{2} \right ) \right ) ^{2}+1 \right ) } \left ( -2\,a{\it RootOf} \left ( \left ( {\it Arcsinh} \left ( {\it \_Z} \right ) \right ) ^{2}{a}^{2}-{{\it \_Z}}^{2}{x}^{2}-2\,{\it Arcsinh} \left ( {\it \_Z} \right ) {\it \_C1}\,a+{{\it \_C1}}^{2}-{x}^{2} \right ) \left ( a{\it Arcsinh} \left ( {\it RootOf} \left ( \left ( {\it Arcsinh} \left ( {\it \_Z} \right ) \right ) ^{2}{a}^{2}-{{\it \_Z}}^{2}{x}^{2}-2\,{\it Arcsinh} \left ( {\it \_Z} \right ) {\it \_C1}\,a+{{\it \_C1}}^{2}-{x}^{2} \right ) \right ) -{\it \_C1} \right ) \sqrt { \left ( {\it RootOf} \left ( \left ( {\it Arcsinh} \left ( {\it \_Z} \right ) \right ) ^{2}{a}^{2}-{{\it \_Z}}^{2}{x}^{2}-2\,{\it Arcsinh} \left ( {\it \_Z} \right ) {\it \_C1}\,a+{{\it \_C1}}^{2}-{x}^{2} \right ) \right ) ^{2}+1}+ \left ( \left ( {\it RootOf} \left ( \left ( {\it Arcsinh} \left ( {\it \_Z} \right ) \right ) ^{2}{a}^{2}-{{\it \_Z}}^{2}{x}^{2}-2\,{\it Arcsinh} \left ( {\it \_Z} \right ) {\it \_C1}\,a+{{\it \_C1}}^{2}-{x}^{2} \right ) \right ) ^{2}+1 \right ) \left ( \left ( {\it RootOf} \left ( \left ( {\it Arcsinh} \left ( {\it \_Z} \right ) \right ) ^{2}{a}^{2}-{{\it \_Z}}^{2}{x}^{2}-2\,{\it Arcsinh} \left ( {\it \_Z} \right ) {\it \_C1}\,a+{{\it \_C1}}^{2}-{x}^{2} \right ) \right ) ^{2}{x}^{2}+{a}^{2}+{x}^{2} \right ) \right ) } \right \} \]