dsolve({(x(t)-y(t))*(x(t)-z(t))*diff(x(t),t) = f(t), (y(t)-x(t))*(y(t)-z(t))*diff(y(t),t) = f(t), (z(t)-x(t))*(z(t)-y(t))*diff(z(t),t) = f(t)})