\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) =0} \]
Mathematica: cpu = 0.003000 (sec), leaf count = 12 \[ \left \{\left \{y(x)\to c_2 x+c_1\right \}\right \} \]
Maple: cpu = 0.0 (sec), leaf count = 9 \[ \left \{ y \left ( x \right ) =x{\it \_C1}+{\it \_C2} \right \} \]