Question

1/2+1/6+1/12+1/20+...+1/x[x+1]

Answer 1

có x mà ko có VP

Answer 2

1/2 + 1/6 + 1/12 + 1/20 + ... + 1/x(x + 1) = 1/1.2 + 1/2.3 + 1/3.4 + 1/4.5 + ... + 1/x(x+1) = 1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 + ... + 1/x - 1/x+1 = 1 - 1/x+1 = x+1/x+1 - 1/x+1 = x/x+1

Answer 3

Ban co the k cho minh ko ?