\[ 4 y^{(4)}(x)-12 y^{(3)}(x)+11 y''(x)-3 y'(x)-4 \cos (x)=0 \] ✓ Mathematica : cpu = 0.102465 (sec), leaf count = 50
\[\left \{\left \{y(x)\to 2 c_1 e^{x/2}+\frac {2}{3} c_2 e^{3 x/2}+c_3 e^x+c_4+\frac {18 \sin (x)}{65}-\frac {14 \cos (x)}{65}\right \}\right \}\] ✓ Maple : cpu = 0.081 (sec), leaf count = 32
\[ \left \{ y \left ( x \right ) ={\it \_C1}\,{{\rm e}^{x}}+2\,{\it \_C2}\,{{\rm e}^{x/2}}+{\frac {2\,{\it \_C3}}{3}{{\rm e}^{{\frac {3\,x}{2}}}}}+{\frac {18\,\sin \left ( x \right ) }{65}}-{\frac {14\,\cos \left ( x \right ) }{65}}+{\it \_C4} \right \} \]