\[ y^{(4)}(x)=0 \] ✓ Mathematica : cpu = 0.00541959 (sec), leaf count = 22
\[\left \{\left \{y(x)\to x \left (x \left (c_4 x+c_3\right )+c_2\right )+c_1\right \}\right \}\]
✓ Maple : cpu = 0.009 (sec), leaf count = 21
\[ \left \{ y \left ( x \right ) ={\frac {{\it \_C1}\,{x}^{3}}{6}}+{\frac {{\it \_C2}\,{x}^{2}}{2}}+{\it \_C3}\,x+{\it \_C4} \right \} \]