Tính:

A=2019/2018 - 2018/2017 + 2017/2016 - 2016/2015

B=1/2019 - 1/2018 + 1/2017 - 1/2016

C=1/2017 - 1/2016 + 1/2015 - 1/2014

Tính :A= [(2018/1)+(2017/2)+(2016/3)+(2015/4)+...+(4/2015)+(3/2016)+(2/2017)+(1/2018)]/[(2019/2)+(2019/3)+(2019/4)+(2019/5)+...+(2019/2015)+(2019/2016)+(2019/2017)+(2019/2018)+(2019/2019)]

Tính :A= [(2018/1)+(2017/2)+(2016/3)+(2015/4)+...+(4/2015)+(3/2016)+(2/2017)+(1/2018)]/[(2019/1)+(2019/2)+(2019/3)+(2019/4)+...+(2019/2015)+(2019/2016)+(2019/2017)+(2019/2018)+(2019/2019)]

so sánh A và B               A=2016/2017-2017/2018+2018/2019-2019/2020                  B=-1/2016-2017 - 1/2018-2019

Cho x,y>0 thỏa mãn

x^2015+y^2015=x^2016+y^2016=x^2017+y^2017

C/m: 1/x^2018+1/y^2018=1/x^2019+1/y^2019

Tìm x 

\(\frac{x-2017}{2015.2016}+\frac{x-2018}{2016.2017}+\frac{x-2019}{2017.2018}+\frac{x-2020}{2018.1019}=\frac{1}{2015}+\frac{1}{2016}+\frac{1}{2017}+\frac{1}{1018}\)

cho A=1/1*2+1/3*4+1/5*6+...+1/2013*2014; B=1/2016+1/2018+1/2020+...+1/4028. A/B=?

A=2017/2018+2020/2019

B=2018/2019+2021/2020

So sánh A và B 

Tính :

a) \(\text{A}=\left(1\times2\right)^{-1}+\left(2\times3\right)^{-1}+...+\left(2014\times2015\right)^{-1}\).

b) \(\text{B}=\frac{2018+\frac{2017}{2}+\frac{2016}{3}+\frac{2015}{4}+...+\frac{2}{2017}+\frac{1}{2018}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+...+\frac{1}{2018}+\frac{1}{2019}}\).