Question

Tính 1/1.3+1/3.5+1/5.7+.......1/2017.2019

Answer 1

=1/2(2/1*3+2/3*5+...+2/2017*2019)

=1/2(1-1/3+1/3-1/5+...+1/2017-1/2019)

=1/2*2018/2019

=1009/2019

Answer 2

=1/2(2/1x3+2/3x5+...+2/2017x2019)

=1/2(1-1/3+1/3-1/5+...+1/2017-1/2019)

=1/2x2018/2019

=1008/2019