\[ y'(x)=x^2 \sqrt {x^2+4 y(x)-4 x}-\frac {x}{2}+1 \] ✓ Mathematica : cpu = 0.804774 (sec), leaf count = 94
DSolve[Derivative[1][y][x] == 1 - x/2 + x^2*Sqrt[-4*x + x^2 + 4*y[x]],y[x],x]
\[\text {Solve}\left [\frac {x^3}{3}-\frac {1}{2} \sqrt {x^2+4 y(x)-4 x}+\log \left (-\sqrt {x^2+4 y(x)-4 x}-x+2\right )-\tanh ^{-1}\left (\frac {2 x-4}{2 \sqrt {x^2+4 y(x)-4 x}}\right )-\frac {1}{2} \log (2-2 y(x))=c_1,y(x)\right ]\] ✓ Maple : cpu = 0.254 (sec), leaf count = 25
dsolve(diff(y(x),x) = -1/2*x+1+x^2*(x^2-4*x+4*y(x))^(1/2),y(x))
\[c_{1}+\frac {2 x^{3}}{3}-\sqrt {x^{2}-4 x +4 y \left (x \right )} = 0\]