\[ y''(x)-f(x) y(x)=0 \] ✗ Mathematica : cpu = 0.116518 (sec), leaf count = 0
DSolve[-(f[x]*y[x]) + Derivative[2][y][x] == 0,y[x],x]
, could not solve
DSolve[-(f[x]*y[x]) + Derivative[2][y][x] == 0, y[x], x]
✗ Maple : cpu = 0. (sec), leaf count = 0
dsolve(diff(diff(y(x),x),x)-f(x)*y(x)=0,y(x))
, result contains DESol or ODESolStruc
\[y \left (x \right ) = \mathit {DESol}\left (\left \{-f \left (x \right ) \textit {\_Y} \left (x \right )+\frac {d^{2}}{d x^{2}}\textit {\_Y} \left (x \right )\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )\]