Можете пожалуйста помочь
f(2) = (1 - 1)/(1 + 1) = 0.
f(4) = (1 - 0)/(1 + 0) = 1.
f(3) = (1 - 5)/(1 + 5) = -4/6 = -2/3.
f(5) = (1 + (2/3))/(1 - (2/3)) = 5.
f(2) + f(4) + f(5) = 0 + 1 + 5 = 6.