Question

1/1 x 2 + 1/2 x 3 + 1/3 x 4 +  .......

 + 1/49 + 1/50

Answer 1

\(...=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{49}-\dfrac{1}{50}\)

\(=1-\dfrac{1}{50}=\dfrac{50}{50}-\dfrac{1}{50}=\dfrac{49}{50}\)

Answer 2

Đề sai rồi em không phải \(\dfrac{1}{49}+\dfrac{1}{50}\) em xem lại đề