\[ \boxed { \phi \left ( f \left ( x,y \left ( x \right ) ,{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ,g \left ( x,y \left ( x \right ) ,{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) \right ) =0} \]
Mathematica: cpu = 0.007001 (sec), leaf count = 23 \[ \text {DSolve}\left [\phi \left (f\left (x,y(x),y'(x)\right ),g\left (x,y(x),y'(x)\right )\right )=0,y(x),x\right ] \]
Maple: cpu = 0.016 (sec), leaf count = 0 \[ \text {could not solve} \]