\[ \left (a+x y'(x)\right )^2-2 a y(x)+x^2=0 \] ✓ Mathematica : cpu = 0.899446 (sec), leaf count = 82
DSolve[x^2 - 2*a*y[x] + (a + x*Derivative[1][y][x])^2 == 0,y[x],x]
\[\text {Solve}\left [\left \{y(x)=\frac {2 a x K[1]+x^2 K[1]^2+a^2+x^2}{2 a},x=\frac {a \log \left (\sqrt {K[1]^2+1}-K[1]\right )}{\sqrt {K[1]^2+1}}+\frac {c_1}{\sqrt {K[1]^2+1}}\right \},\{y(x),K[1]\}\right ]\] ✓ Maple : cpu = 8.938 (sec), leaf count = 78
dsolve((x*diff(y(x),x)+a)^2-2*a*y(x)+x^2 = 0,y(x))
\[y \left (x \right )-\operatorname {RootOf}\left (-a \,\operatorname {arcsinh}\left (\frac {\operatorname {RootOf}\left (-2 a y \left (x \right )+a^{2}+x^{2}+2 \textit {\_Z} a +\textit {\_Z}^{2}\right )}{x}\right )-x \sqrt {\frac {a \left (-2 \operatorname {RootOf}\left (-2 a y \left (x \right )+a^{2}+x^{2}+2 \textit {\_Z} a +\textit {\_Z}^{2}\right )+2 \textit {\_Z} -a \right )}{x^{2}}}+c_{1}\right ) = 0\]