\[ b x \left (x^2-a^2\right ) y'(x)^2+\left (x^2-a^2\right ) y'(x)^3+b x+y'(x)=0 \] ✓ Mathematica : cpu = 0.0168187 (sec), leaf count = 64
\[\left \{\left \{y(x)\to c_1-\frac {b x^2}{2}\right \},\left \{y(x)\to c_1-\tan ^{-1}\left (\frac {x}{\sqrt {a^2-x^2}}\right )\right \},\left \{y(x)\to \tan ^{-1}\left (\frac {x}{\sqrt {a^2-x^2}}\right )+c_1\right \}\right \}\] ✓ Maple : cpu = 0.047 (sec), leaf count = 52
\[ \left \{ y \left ( x \right ) =-{\frac {b{x}^{2}}{2}}+{\it \_C1},y \left ( x \right ) =-\arctan \left ( {x{\frac {1}{\sqrt {{a}^{2}-{x}^{2}}}}} \right ) +{\it \_C1},y \left ( x \right ) =\arctan \left ( {x{\frac {1}{\sqrt {{a}^{2}-{x}^{2}}}}} \right ) +{\it \_C1} \right \} \]