Question

tính dùm ạ

1/1*2+1/2*3+1/3*4+......+1/2017*2018

mn giúp e nhanh nhanh xí đk ko ạ

Answer 1

đăt A= đề bài ta có A=1-1/2+1/2-1/3+1/3-1/4+...+1/2017-1/2018

A=1-1/2018=2017/2018

Answer 2

Ta có : 

\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2017.2018}\)

\(=\)\(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2017}-\frac{1}{2018}\)

\(=\)\(1-\frac{1}{2018}\)

\(=\)\(\frac{2017}{2018}\)

Chúc bạn học tốt ~ 

Answer 3

     1/1×2 + 1/2×3 + 1/3×4 +......+ 1/2017×2018

= 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 +.......+ 1/2017 -                1/2018

= 1 - 1/2018

= 2017/2018

Answer 4

nhgjnmhgjku