=1-1/3+1/3-1/5+...+1/2015-1/2017
=1-1/2017
=2016/2017
Đúng 1
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=1-1/3+1/3-1/5+...+1/2015-1/2017
=1-1/2017
=2016/2017
-2/1.3-2/3.5-2/5.7-2/7.9-.....-2/2015.2017-1/27
1.3+3.5+5.7+..........+2015.2017
Tính nhanh:
1.3+3.5+5.7 +......+2015.2017
1/1.3+1/3.5+1/5.7+....+1/2015.2017
2016/1.3 + 2016/3.5 + 2016/5.7 +...+ 2016/2015.2017=?
\(\dfrac{2}{3.5}+\)\(\dfrac{2}{5.7}+\dfrac{2}{7.9}\)\(+...+\dfrac{2}{2015.2017}\)
\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2015.2017}\)
Tinh tổng:
a) 2/1.3+2/3.5+2/5.7+.........2/99.101
b) 5/1.3+5/3.5+5/5.7+....................5/99.101
tính tổng :
a.2/1.3+2/3.5+2/5.7+....+2/99.101
b.5/1.3+5/3.5+5/5.7+....+5/99.101