S=\(\dfrac{5}{1.2}\)+\(\dfrac{13}{2.3}\)+\(\dfrac{25}{3.4}\)+\(\dfrac{41}{4.5}\)+...+\(\dfrac{181}{9.10}\)
CMR:\(\frac{3}{\left(1.2\right)^2}+\frac{5}{\left(2.3\right)^2}+\frac{7}{\left(3.4\right)^2}+...+\frac{19}{\left(9.10\right)^2}< 1\)
Tính:
A = \(\frac{7}{3.4}\) - \(\frac{9}{4.5}\) + \(\frac{11}{5.6}\) - \(\frac{13}{6.7}\) + \(\frac{15}{7.8}\) - \(\frac{17}{8.9}\) + \(\frac{19}{9.10}\)
Tính
\(\left(1-\frac{2}{2.3}\right)\left(1-\frac{2}{3.4}\right)\left(1-\frac{2}{4.5}\right)...\left(1-\frac{2}{99.100}\right)\)
Cho \(M=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)
\(N=\frac{2016}{51}+\frac{2016}{52}+...+\frac{2016}{100}\)
CMR N chia hết cho M.
1,Tìm GTNN của
C= 2|x-3|+2x+5
D=|x+1|+|x-5|
2, Tính \(\frac{A}{B}\)
A=\(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{4.5}+.....+\frac{1}{19.20}\)
B=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+..........+\frac{1}{19}+\frac{1}{20}\)
Ai giải được bài nào thì giải giúp mk vs (viết đầy đủ giúp mk tí )
chứng minh rằng:
\(\frac{1.2-1}{2!}+\frac{2.3-1}{3!}+\frac{3.4-1}{4!}+...+\frac{99.100-1}{100!}< 2\)
mình ngu toán chúng minh (hép mi)
Rút gọn:
a/ \(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2009.2000}\)
b/ \(B=\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{1998.1999.2000}\)
c/ \(C=\frac{1}{2.4}+\frac{1}{4.6}+\frac{1}{6.8}+...+\frac{1}{2006.2008}\)
cho A= \(\frac{1}{1.2^2}+\frac{1}{2.3^2}+\frac{1}{3.4^2}+...+\frac{1}{49.50^2}\)
B= \(\frac{1}{2^{ }}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{50^2}\)
Chứng minh : A < \(\frac{1}{2}\)<B
