Question

Tính nhanh: 1/1*2+1/2*3+1/3*4+...+1/2016*2017

 

 

Answer 1

=1/1-1/2+1/2-1/3+....+1/2016-1/2017

=1/1-1/2017=2016/2017

Answer 2

= 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ........+ 1/2016 - 1/2017

= 1 - 1/2017 

= 2016/2017

Answer 3

\(\frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+...+\frac{1}{2016\times2017}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2016}-\frac{1}{2017}\)

\(=1-\frac{1}{2017}\)

\(=\frac{2016}{2017}\)

Học tốt #

Answer 4

A=1009