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\(=\left(-\frac{5}{132}-\frac{5}{3}\right)-\left(-\frac{5}{4}+\frac{6}{11}\right)\)
\(=-\frac{75}{44}-\left(-\frac{5}{4}+\frac{6}{11}\right)\)
\(=-\frac{75}{44}+\frac{31}{44}\)
\(=-1\)
( \(\frac{-1}{4}\)+ \(\frac{7}{33}\)- \(\frac{5}{3}\) ) - ( \(\frac{-5}{4}\) + \(\frac{6}{11}\))
= ( \(\frac{-1}{4}\)\(\frac{-48}{33}\)) - ( \(\frac{-31}{44}\))
= \(\frac{-1}{4}\)+ \(\frac{-48}{33}\)+ \(\frac{-31}{44}\)
= ( \(\frac{-1}{4}\)+ \(\frac{-31}{44}\)) + \(\frac{-48}{33}\)
= \(\frac{-5}{11}\) + \(\frac{-48}{33}\)
= \(\frac{-21}{11}\)
HỌC TỐT ^^__^^
\(A=3-\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-\frac{1}{20}-\frac{1}{30}-\frac{1}{42}-\frac{1}{56}\)
\(A=3-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}\right)\)
\(A=3-\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}\right)\)
\(A=3-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}\right)\)
\(A=3-\left(1-\frac{1}{8}\right)\)
\(A=3-\frac{5}{8}\)
\(A=\frac{19}{8}\)
Đặt A = \(\frac{1}{1.6}+\frac{1}{6.11}+..+\frac{1}{\left(5n+1\right)\left(5n+6\right)}\)
5A = \(\frac{5}{1.6}+\frac{5}{6.11}+..+\frac{5}{\left(5n+1\right)\left(5n+6\right)}\)
= \(\frac{1}{1}-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+..+\frac{1}{5n+1}-\frac{1}{5n+6}\)
= \(\frac{1}{1}-\frac{1}{5n+6}=\frac{5n+6-1}{5n+6}=\frac{5n+5}{5n+6}=\frac{5\left(n+1\right)}{5n+6}\)
=> A = \(=\frac{5\left(n+1\right)}{5n+6}:5=\frac{5\left(n+1\right)}{5n+6}\cdot\frac{1}{5}=\frac{n+1}{5n+6}\)
VẬy VT = VP ĐT Đ CM
Ta có :(33/5-45/14):35/6]/(21-1,25):2,5
=(711/1225)/(79/10)
=1542/19355
5% của 1542/19355 là 771/193550