x + 1/y = 1 则：y = 1/(1-x)z + 1/x = 1 则：z = 1- 1/x = (x-1)/x ,所以,1/z = x/(x-1) = 1+ 1/(x-1) = 1-1/(1-x)所以 y + 1/z = 1(x-4)/(x-5) - (x-5)/(x-6) = (x-7)/(x-8) - (x-8)(x-9)即：1+1/(x-5) - 1 - 1/(x...