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\(B=\frac{1}{16}+\frac{6}{16.26}+\frac{6}{26.36}+...+\frac{6}{2006.2016}\)
\(B=\frac{1}{16}+6\left(\frac{1}{16.26}+\frac{6}{26.36}+...+\frac{6}{2006.2016}\right)\)
\(B=\frac{1}{16}+\frac{6}{10}\left(\frac{1}{16}-\frac{1}{26}+\frac{1}{26}-\frac{1}{36}+...+\frac{1}{2006}-\frac{1}{2016}\right)\)
\(B=\frac{1}{16}+\frac{6}{10}\left(\frac{1}{16}-\frac{1}{2016}\right)\)
\(B=\frac{1}{16}+\frac{6}{10}.\frac{125}{2016}\)
\(B=\frac{1}{16}+\frac{25}{672}\)
\(B=\frac{67}{672}\)
A = 3 + 6 + 9 + ... + 2007
=>A = 3( 1 + 2 + 3 + ... + 669 )
=> A = \(3\cdot\left(\frac{670\cdot669}{2}\right)\)
=> A = \(3\cdot224115\)= 672345
B = \(2\cdot53\cdot12+4\cdot6\cdot87-3\cdot8\cdot40\)
=> B = 24 * 53 + 24 * 87 - 24 * 40
=> B = 24 * ( 53 + 87 - 40 )
=> B = 24 * 100 = 2400
c) ta có Tử số = \(2006\cdot\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2007}\right)\)
Mẫu số = \(\frac{2007-1}{1}\)+\(\frac{2007-2}{2}\)+...+\(\frac{2007-2006}{2006}\)
=> Mẫu số = \(\frac{2007}{1}\)\(-1\)+ \(\frac{2007}{2}\)\(-1\)+ ... + \(\frac{2007}{2006}\)\(-1\)
=> Mẫu số = \(\frac{2007}{1}\)+ \(\frac{2007}{2}\)+ ... + \(\frac{2007}{2006}\)- ( 1 + 1 + 1 + ... + 1 ) ( 1 + 1 + ... + 1 có 2006 số hạng 1 )
=> Mẫu số = ( 2007 - 2006 ) + \(2007\cdot\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2006}\right)\)
=> Mẫu số = \(\frac{2007}{2007}\)+ \(2007\cdot\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2006}\right)\)
=> Mẫu số = \(2007\cdot\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2007}\right)\)
=> C = \(\frac{TS}{MS}\)= \(\frac{2006}{2007}\)
\(\frac{15.\left(\frac{1}{616}.\frac{1}{6.16}.\frac{1}{6.16}\right)}{33.\left(\frac{1}{6.16}.\frac{1}{6.16}.\frac{1}{6.16}\right)}=\frac{15}{35}\)
\(A=\frac{\frac{3}{2}\left(\frac{1}{6}-\frac{1}{16}+\frac{1}{16}-\frac{1}{26}+\frac{1}{26}-\frac{1}{36}\right)}{\frac{33}{10}\left(\frac{1}{6}-\frac{1}{16}+\frac{1}{16}-\frac{1}{26}+\frac{1}{26}-\frac{1}{36}\right)}=\frac{\frac{3}{2}}{\frac{33}{10}}=\frac{3}{2}:\frac{33}{10}=\frac{5}{11}\)
Ta có:\(A=\frac{\frac{15}{6.16}+\frac{15}{16.26}+\frac{15}{26.36}}{\frac{33}{6.16}+\frac{63}{16.26}+\frac{93}{26.36}}\)
=>\(A=\frac{\left(\frac{1}{6.16}+\frac{1}{16.26}+\frac{1}{26.36}\right).15}{\frac{33}{6.16}+\frac{\frac{21}{11}.33}{16.26}+\frac{\frac{31}{11}.33}{26.36}}\)
=>\(A=\frac{\left(\frac{1}{6.16}+\frac{1}{16.26}+\frac{1}{26.36}\right).15}{\frac{21}{11}.\frac{31}{11}.33.\left(\frac{1}{6.16}+\frac{1}{16.26}+\frac{1}{26.36}\right)}\)
=>\(A=\frac{15}{\frac{21}{11}.\frac{31}{11}.33}\)
=>\(A=\frac{15}{\frac{1953}{11}}\)
=>\(A=\frac{55}{651}\)
Vậy \(A=\frac{55}{651}\)
bạn tính theo sai phân hữu hạng ý.rút tử ra ngoai để mẫu là 1
\(\frac{\frac{15+15+15}{6\cdot32}}{\frac{33+63+93}{6\cdot32}}=\frac{\frac{45}{216}}{\frac{63}{216}}=\frac{45}{63}=\frac{5}{7}\)
(tử mẩu đều có số giống nhau thì gạch nha)
nhanh lên ngày mai mk hk rùi