\[ y(x) y''(x)-a y'(x)^2=0 \] ✓ Mathematica : cpu = 0.107333 (sec), leaf count = 26
\[\left \{\left \{y(x)\to c_2 (-a x+x-c_1){}^{\frac {1}{1-a}}\right \}\right \}\] ✓ Maple : cpu = 0.37 (sec), leaf count = 25
\[ \left \{ y \left ( x \right ) = \left ( {\frac {1}{ \left ( 1-a \right ) \left ( {\it \_C1}\,x+{\it \_C2} \right ) }} \right ) ^{ \left ( a-1 \right ) ^{-1}} \right \} \]