Dễ thôi:
Khoảng cách là 2
\(\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+....+\frac{1}{2015}-\frac{1}{2017}\right)\)
\(\frac{1}{2}.\left(1-\frac{1}{2017}\right)=\frac{1}{2}.\frac{2016}{2017}=\frac{1008}{2017}\)
cảm ơn bạn đã giúp mình!!
\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2015.2017}\)
-2/1.3-2/3.5-2/5.7-2/7.9-.....-2/2015.2017-1/27
\(ChoA=\left(1+\frac{1}{1.3}\right).\left(1+\frac{1}{3.5}\right).\left(1+\frac{1}{5.7}\right).....\left(1+\frac{1}{2015.2017}\right)\)
1.3+3.5+5.7+..........+2015.2017
2/1.3 + 2/3.5 + 2/5.7 + ... + 2/2015.2017
Tính nhanh:
1.3+3.5+5.7 +......+2015.2017
2016/1.3 + 2016/3.5 + 2016/5.7 +...+ 2016/2015.2017=?
Tính tổng các ps sau
a,\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2017.2018}\)
b,\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2015.2017}\)
B=1/1.3+1/3.5+...+1/2015.2017