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\(\frac{2010.2011-1005}{2010.2010+1005}\)= \(\frac{2010.\left(2010+1\right)-1005}{2010.2010+1005}\)= \(\frac{2010.2010+2010-1005}{2010.2010+1005}\)= \(\frac{2010.2010+1005}{2010.2010+1005}\)=1
\(A=\frac{m^{2010}+1}{m^{2011}+1};B=\frac{m^{2011}+1}{m^{2012}+1}\)
Ta có:
\(A=\frac{m^{2010}+1}{m^{2011}+1}\Rightarrow10A=\frac{m^{2011}+10}{m^{2011}+1}\)
\(B=\frac{m^{2011}+1}{m^{2012}+1}\Rightarrow10B=\frac{m^{2012}+10}{m^{2012}+1}\)
Hay ta so sánh: \(\frac{9}{m^{2011}};\frac{9}{m^{2012}}\)
Vì \(2011< 2012\)nên \(m^{2011}< m^{2012}\)hay \(\frac{9}{m^{2011}}>\frac{9}{m^{2012}}\)
Vậy \(A>B\)
\(=\frac{4}{5.7}+\frac{4}{7.9}+\frac{4}{9.11}+...+\frac{4}{59.61}\)
\(=2.\left(\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{59.61}\right)\)
\(=2.\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+...+\frac{1}{59}-\frac{1}{61}\right)\)
=\(2.\left(\frac{1}{5}-\frac{1}{61}\right)\)
\(=2.\left(\frac{36}{505}\right)\)
\(=\frac{72}{505}\)
TK nha !!
Ta có : \(\frac{4}{5.7}+\frac{4}{7.9}+\frac{4}{9.11}+....+\frac{4}{59.61}\)
\(=2\left(\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}+.....+\frac{2}{59.61}\right)\)
\(=2\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+.....+\frac{1}{59}-\frac{1}{61}\right)\)
\(=2\left(\frac{1}{5}-\frac{1}{61}\right)\)
\(=2.\frac{56}{305}=\frac{112}{305}\)
Ta có : \(\frac{151515}{-313131}=\frac{151515:10101}{-313131:10101}=\frac{15}{-31}=-\frac{15}{31}\)
Vậy \(-\frac{15}{31}=\frac{151515}{-313131}\)
17A = \(\frac{17^{2009}+17}{17^{2009}+1}=1+\frac{16}{17^{2009}+1}\)
17B = \(\frac{17^{2010}+17}{17^{2010}+1}=1+\frac{16}{17^{2010}+1}\)
mà \(\frac{16}{17^{2009}+1}>\frac{16}{17^{2010}+1}\)
=> A > B
B < 17 ^ 2009 + 1 + 16 / 17^2010 + 1+16 = 17^2009 + 17 / 17^2010 + 17 = 17(17^2008 + 1) / 17(17^2009+1) = 17^2008 + 1 / 17^2009 + 1 =A
=> B < A
****** k mk nha!
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