1/1.3+1/3.5+1/5.7+...+1/99.101
A=1/1.3+1/3.5+1/5.7+....+1/99.101
tính tổng sau
M=2/1.3+2/3.5+2/5.7+...+2/99.101
A=7/10.11+7/11.12+7/12+13+...7/69.70
B=1/25.27+1/27.29+1/29.31+...+1/73.75
1. Tính nhanh các tổng sau :
a) 1/5.6 +1/6.7+1/7.8+...+1/24.25
b) 2/1.3+2/3.5+2/5.7+...+2/99.101
c) 3/1.4+3/4.7+...+3/2002.2005
d) 5/2.7+5/7.12+...+5/1997.2002
a) 1/1.3+1/3.5+1/5.7
b) 1/1.3+1/3.5+1/5.7+...+1/2007.2009+1/2009.2011
s=1.3+2.4+3.5+...+99.101
Tính
1.3+2.4+3.5+...+99.101
Tính Nhanh : a) \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+....+\frac{1}{99.101}\)
b) \(\frac{1}{3.6}+\frac{1}{6.9}+\frac{1}{9.12}+\frac{1}{12.15}\)
c, C = 2/1.3 + 2/3.5 + 2/5.7 + .......+ 2/69.71+ 2/71.73
