\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) + \left ( P \left ( x \right ) +l \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 0.157020 (sec), leaf count = 18 \[ \text {DSolve}\left [y(x) (l+P(x))+y''(x)=0,y(x),x\right ] \]
Maple: cpu = 0.0 (sec), leaf count = 23 \[ \left \{ y \left ( x \right ) ={\it DESol} \left ( \left \{ \left ( P \left ( x \right ) +l \right ) {\it \_Y} \left ( x \right ) +{\frac { {\rm d}^{2}}{{\rm d}{x}^{2}}}{\it \_Y} \left ( x \right ) \right \} , \left \{ {\it \_Y} \left ( x \right ) \right \} \right ) \right \} \]