\(=\frac{1.2}{99.100}\)
\(=\frac{2}{9900}=\frac{1}{4950}\)
\(=\frac{1.2}{99.100}\)
\(=\frac{2}{9900}=\frac{1}{4950}\)
Tính biểu thức A
\(A=\frac{5}{1\times2}+\frac{5}{2\times3}+\frac{5}{3\times4}+...+\frac{5}{98\times99}+\frac{5}{99\times100}\)
\(y=\frac{1\times100+2\times99+3\times98...+99\times2+100\times1}{1\times2+2\times3+3\times4+...+99\times100+100\times101}=?\)
CHO A = \(\frac{2\times9\times8+3\times12\times10+4\times15\times12+...+98\times297\times200}{2\times3\times4+3\times4\times5+4\times5\times6+...+98\times99\times100}\)
TÍNH A\(^2\)
tìm x biết
\(\frac{x\times\left(1\times2+2\times3+3\times4+...+98\times99\right)}{98\times100\times33}=2010-|-2011|\)
Tính :
A = \(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\)
B = \(\frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+...+\frac{1}{98\times99}+\frac{1}{99\times100}\)
Tính\(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+\frac{1}{3\times4\times5}+...\frac{1}{2014\times2015\times2016}\)
\(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+\frac{1}{3\times4\times5}+...+\frac{1}{2014\times2015\times2016}=?\)
Cho B= \(\frac{1\times2}{1\times2\times3}+\frac{1\times2}{1\times2\times4}+\frac{1\times2}{1\times2\times3\times4}+\frac{1\times2}{1\times2\times3\times4\times5}+....+\frac{1\times2}{n,giao}\left(n\in N,n\ge3\right)\)
chứng tỏ B nhỏ hơn 3
Cho A=\(\frac{1\times2-1}{2!}+\frac{2\times3-1}{3!}+\frac{3\times4-1}{4!}+.....+\frac{99\times100-1}{100!}<2\)