\[ x \left (y''(x)+y(x)\right )-\cos (x)=0 \] ✓ Mathematica : cpu = 0.0289538 (sec), leaf count = 41
\[\left \{\left \{y(x)\to c_2 \sin (x)+c_1 \cos (x)+\frac {1}{2} (\text {Ci}(2 x) \sin (x)-\text {Si}(2 x) \cos (x)+\log (x) \sin (x))\right \}\right \}\]
✓ Maple : cpu = 0.046 (sec), leaf count = 35
\[ \left \{ y \left ( x \right ) ={\frac {\sin \left ( x \right ) {\it Ci} \left ( 2\,x \right ) }{2}}-{\frac {{\it Si} \left ( 2\,x \right ) \cos \left ( x \right ) }{2}}+{\frac { \left ( 2\,{\it \_C2}+\ln \left ( x \right ) \right ) \sin \left ( x \right ) }{2}}+\cos \left ( x \right ) {\it \_C1} \right \} \]