= 1/2. ( 1 - 1/3 + 1/3 - 1/5 + 1/5 -1/7 +........+ 1/2013 - 1/2015)
= 1/2 . ( 1- 1/2015)
= 1007/2015
= 1/2. ( 1 - 1/3 + 1/3 - 1/5 + 1/5 -1/7 +........+ 1/2013 - 1/2015)
= 1/2 . ( 1- 1/2015)
= 1007/2015
Thực hiện phép tính: \(2.\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{99.100}\right)\)
Thực hiện phép tinh sau:
\(\frac{1}{1.3}+\frac{1}{2.4}+\frac{1}{3.5}+\frac{1}{4.6}+\frac{1}{5.7}+\frac{1}{6.8}+\frac{1}{7.9}+\frac{1}{8.10}\)
Tính tổng Q:
\(\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+....+\frac{1}{2013.2015}\)
TÍnh giá trị biểu thúc:
M =\(\frac{1}{15}\)+\(\frac{1}{35}\) +...+ \(\frac{1}{2499}\)
N = \(\frac{-5}{1.3}\)+\(\frac{-5}{3.5}\)+\(\frac{-5}{5.7}\)+ ... + \(\frac{-5}{2013.2015}\)
\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2015.2017}\)
\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+....+\frac{1}{2003.2005}\)
Tính nhanh \(\frac{1.3}{3.5}\)+\(\frac{2.4}{5.7}\)\(+\frac{3.5}{7.9}+....+\frac{2013.2015}{4027.4029}\)
\(P=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{29.31}\)
\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{7}{5.7}+...+\frac{1}{99.101}\)