kill(all)$

van=facebook.com/LearningCalculus$

f(t):=2-1/(2-(1/(2-1/t)));

solve(f(t),t);

u=f(t);

g(u):=''(rhs(first(solve(u=f(t),t))))$ 'g(u) = g(u);

x:g(2/3); y:g(1/2); z:g(0); x+y+z;