\[ -\text {Global$\grave { }$f}(\text {Global$\grave { }$x})^2+\text {Global$\grave { }$y}'(\text {Global$\grave { }$x})^2+\text {Global$\grave { }$y}(\text {Global$\grave { }$x})^2=0 \] ✗ Mathematica : cpu = 17.3005 (sec), leaf count = 0 , could not solve
DSolve[-Global`f[Global`x]^2 + Global`y[Global`x]^2 + Derivative[1][Global`y][Global`x]^2 == 0, Global`y[Global`x], Global`x]
✗ Maple : cpu = 0. (sec), leaf count = 0 , could not solve
dsolve(diff(y(x),x)^2+y(x)^2-f(x)^2 = 0,y(x))