\[ a y(x)^2-b+y'(x)=0 \] ✓ Mathematica : cpu = 5.2031 (sec), leaf count = 32
\[\left \{\left \{y(x)\to \frac {\sqrt {b} \tanh \left (\sqrt {a} \sqrt {b} \left (c_1+x\right )\right )}{\sqrt {a}}\right \}\right \}\]
✓ Maple : cpu = 0.052 (sec), leaf count = 23
\[ \left \{ y \left ( x \right ) ={\frac {1}{a}\tanh \left ( \sqrt {ab} \left ( x+{\it \_C1} \right ) \right ) \sqrt {ab}} \right \} \]
\begin {align*} y^{\prime }+ay^{2}-b & =0\\ \frac {dy}{dx} & =b-ay^{2} \end {align*}
Separable,\begin {align*} \frac {dy}{b-ay^{2}} & =dx\\ \int \frac {dy}{b-ay^{2}} & =\int dx \end {align*}
But \[ \int \frac {dy}{b-ay^{2}}=\frac {1}{\sqrt {ab}}\tanh ^{-1}\left ( \sqrt {\frac {a}{b}}y\right ) \] Hence\begin {align*} \frac {1}{\sqrt {ab}}\tanh ^{-1}\left ( \sqrt {\frac {a}{b}}y\right ) & =x+C\\ \tanh ^{-1}\left ( \sqrt {\frac {a}{b}}y\right ) & =\sqrt {ab}\left ( x+C\right ) \\ \sqrt {\frac {a}{b}}y & =\tanh \left ( \sqrt {ab}\left ( x+C\right ) \right ) \\ y & =\sqrt {\frac {b}{a}}\tanh \left ( \sqrt {ab}\left ( x+C\right ) \right ) \end {align*}