\[ y^{(4)}(x)=0 \] ✓ Mathematica : cpu = 0.0027568 (sec), leaf count = 24
\[\left \{\left \{y(x)\to c_4 x^3+c_3 x^2+c_2 x+c_1\right \}\right \}\] ✓ Maple : cpu = 0.115 (sec), leaf count = 21
\[ \left \{ y \left ( x \right ) ={\frac {{\it \_C1}\,{x}^{3}}{6}}+{\frac {{\it \_C2}\,{x}^{2}}{2}}+{\it \_C3}\,x+{\it \_C4} \right \} \]