\(\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{2004.2005.2006}\)
\(=\frac{2}{1.2}-\frac{2}{2.3}+\frac{2}{2.3}-\frac{2}{3.4}+...+\frac{2}{2004.2005}-\frac{2}{2005.2006}\)
\(=\frac{2}{1.2}-\frac{2}{2005.2006}\)
\(=1-\frac{1}{2011015}\)
\(=\frac{2011015}{2011015}-\frac{1}{2011015}\)
\(=\frac{2011014}{2011015}\)
Cbht
\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+...+\frac{1}{2004.2005.2006}\)
Tính C = \(\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{98.99.100}\)
S=\(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+..........+\frac{2}{2009.2010.2011}\)
Tính S
Tính giá trị
\(C=\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{98.99.100}\)
\(A=\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{37.38.39}\)
Tìm A.
tìm x
\(\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{19.20.21}\right).x=5\)
so sánh :S= \(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{2010.2011.2012}\)với P=\(\frac{1}{2}\)
Tính1/ 1.2.3+ 1/ 2.3.4+ ....... +1/2004.2005.2006
So sánh:
S=\(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{2009.2010.2011}\)và P=\(\frac{1}{2}\)
