\(B=\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+...+\frac{1}{2013\times2015}\\
2B=\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+...+\frac{2}{2013\times2015}\\
2B=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2013}-\frac{1}{2015}\\2B=1-\frac{1}{2015}=\frac{2014}{2015}\\
\Rightarrow B=\frac{2014}{2015}
\div2=\frac{1007}{2015}\)
Tính:
A = 1/1.3+1/3.5+1/5.7+....+1/2013.2015
Thực hiện phép tính:
B =\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2013.2015}\)
\(\text{M=1-1/1.3-1/3.5-1/5.7-...-1/2013.2015}\)
bai 1 tinh tong
a)1/5.6+1/6.7+1/7.8+.......+1/99.100
b)2/1.3+2/3.5+2/5.7+.........+2/2013.2015
A, m= 4/1.3+4/3.5+4/5.7+....+4/2013.2015
b,S=2/5.9+2/9.13+2/13.17+....+2/97.101
c,A=1/5.6+1/6.7+1/7.8+......+1/24.25
d,B=2/1.3+2/3.5+2/5.7+....+2/99.101
e,C=52/1.6+52/6.11+52/11.16+52/16.21+52/21.26+52/26.31
Tính tổng 4/1.3+4/3.5+4/5.7+4/7.9+4/9.11+.....+4/2013.2015
CMR : Với n \(\in\) N* thì 1/n . 1/n+1 = 1/n - 1/n+1
Áp dụng hãy tính :
a, S= 1/1.2 + 1/2.3 + 1/3.4 + 1/4.5 + ... + 1/ 2015.2016
b, S1= 1/1.3 + 1/3.5 + 1/5.7 + 1/7.9 +...+ 1/2013.2015
tính tổng:
Q= 1/3.5 + 1/5.7+ 1/9.7+...........+1/2013.2015.
tính
\(B=\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{97.99}\)
