\[ \boxed { x{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +{x}^{a} \left ( y \left ( x \right ) \right ) ^{2}+1/2\, \left ( a-b \right ) y \left ( x \right ) +{x}^{b}=0} \]
Mathematica: cpu = 0.036505 (sec), leaf count = 40 \[ \left \{\left \{y(x)\to -x^{\frac {b-a}{2}} \tan \left (\frac {2 x^{\frac {a+b}{2}}}{a+b}-c_1\right )\right \}\right \} \]
Maple: cpu = 0.046 (sec), leaf count = 42 \[ \left \{ y \left ( x \right ) =-{1\tan \left ( {\frac {1}{a+b} \left ( { \it \_C1}\,a+{\it \_C1}\,b+2\,{x}^{a/2+b/2} \right ) } \right ) \left ( {x}^{{\frac {a}{2}}-{\frac {b}{2}}} \right ) ^{-1}} \right \} \]