\[ a y'(x)^m+b y'(x)^n-y(x)=0 \] ✓ Mathematica : cpu = 0.270773 (sec), leaf count = 56
\[\text {Solve}\left [\left \{x=\frac {a m K[1]^{m-1}}{m-1}+\frac {b n K[1]^{n-1}}{n-1}+c_1,y(x)=a K[1]^m+b K[1]^n\right \},\{y(x),K[1]\}\right ]\] ✓ Maple : cpu = 0.063 (sec), leaf count = 36
\[\left \{-c_{1}+x -\left (\int _{}^{y \left (x \right )}\frac {1}{\RootOf \left (-a \,\textit {\_Z}^{m}-b \,\textit {\_Z}^{n}+\textit {\_a} \right )}d \textit {\_a} \right ) = 0, y \left (x \right ) = 0\right \}\]