\(C=1.3+3.5+5.7+...+23.25\)
\(6C=1.3.\left(1+5\right)+3.5.\left(7-1\right)+5.7.\left(9-3\right)+...+23.25.\left(27-21\right)\)
\(6C=1.3+1.3.5+3.5.7-1.3.5+5.7.9-3.5.7+...+23.25.27-21.23.25\)
\(6C=3+23.25.27\)
\(6C=3+15525\)
\(6C=15528\)
\(C=\frac{15528}{6}=2588\)
Rút gọn biểu thức
A=-2/1.3-2/3.5-2/5.7-....-2/19.21-2/23.25-2/25.27-1/27
A=........
rút gọn biểu thức
A= -2/1.3-2/3.5-2/5.7-..-2/19.21-2/23.25-2/25.27-1/27
ta được A=
B=1/3.5+1/5.7+1/7.9+....+1/21.23+1/23.25
Tìm a
\(\left(a+\frac{1}{1.3}\right)+\left(a+\frac{1}{3.5}\right)+\left(a+\frac{1}{5.7}\right)+...+\left(a+\frac{1}{23.25}\right)=11.a+\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\right).\)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
c) 4/2.4+4/4.6+4/6.8+...+4/2008.2010
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
c, C = 2020/1.2 + 2020/2.3 + 2020/3.4 + ... + 2020/2019.2020
d, D = 2020/1.3 + 2020/3.5 + 2020/5.7 + ... + 2020/2019.2021
e, E = 2023/ 1.3 + 2023/3.5 + 2023/5.7 + ... + 2023/2019.2020
f, F = 1/15 + 1/35 + 1/63 + ... + 1/657
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