\[ y'(x)=\frac {e^{2 x/3}}{e^{-2 x/3} y(x)+1} \] ✓ Mathematica : cpu = 0.156525 (sec), leaf count = 85
\[\text {Solve}\left [7 \left (3 \log \left (-\frac {2}{3} e^{-4 x/3} y(x)^2-\frac {2}{3} e^{-2 x/3} y(x)+1\right )+4 x-9 c_1\right )=6 \sqrt {7} \tanh ^{-1}\left (\frac {y(x)+4 e^{2 x/3}}{\sqrt {7} \left (y(x)+e^{2 x/3}\right )}\right ),y(x)\right ]\] ✓ Maple : cpu = 2.969 (sec), leaf count = 52
\[ \left \{ y \left ( x \right ) ={{\it RootOf} \left ( -{{\rm e}^{{\it RootOf} \left ( -343\, \left ( \tanh \left ( 1/6\, \left ( 4\,{\it \_C1}-4\,x-3\,{\it \_Z} \right ) \sqrt {7} \right ) \right ) ^{2}+343+98\,{{\rm e}^{{\it \_Z}}} \right ) }}-3+2\,{\it \_Z}+2\,{{\it \_Z}}^{2} \right ) \left ( {{\rm e}^{-{\frac {2\,x}{3}}}} \right ) ^{-1}} \right \} \]