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Ta có:
2010 . 2011/2010 . 2011 + 1 2009 . 2010/2009 . 2010 + 1
= 1 - 1/2010 . 2011 + 1 = 1 - 1/2009 . 2010 + 1
Vì 2010 . 2011 + 1 > 2009 . 2010 + 1
=> 1/2010 . 2011 + 1 < 1/2009 . 2010 + 1
=> 1 - 1/2010 . 2011 + 1 > 1 - 1/2009 . 2010 + 1
=> 2010.2011/2010.2011+1 > 2009.2010/2009.2010+1
Ta có: 2009.2010>2008.2009
\(\frac{1}{2009\cdot2010}< \frac{1}{2008\cdot2009}\)
\(\Rightarrow E>F\)
A = \(\frac{2009.2010-2}{2008+2008.2010}=\frac{2009.2010-2}{2008.\left(2010+1\right)}=\frac{2009.2010-2}{2008.2011}=\frac{2008.2010+2010-2}{2008.2011}=\frac{2008.2011}{2008.2011}=1\)
B = \(\frac{-2009.20102010}{20092009.2010}=\frac{-2009.10001.2010}{2009.10001.2010}=-1\)
1 > -1 => A > B
Ta có:
\(A=\frac{2009.2010-2}{2008+2008.2010}\)
\(A=\frac{\left(2008+1\right).2010-2}{2008+2008.2010}\)
\(A=\frac{2008.2010+2010-2}{2008+2008.2010}\)
\(A=\frac{2008.2010+2008}{2008+2008.2010}\)
\(A=1\)
\(B=\frac{-2009.20102010}{20092009.2010}\)
\(B=\frac{-2009.2010.10001}{2009.10001.2010}\)
\(B=-1\)
Vì \(1>-1\Rightarrow A>B\)
Vậy \(A>B\)
\(A=\left(1-\frac{1}{2010}\right)-\left(1-\frac{1}{2011}\right)+\left(1-\frac{1}{2012}\right)-\left(1-\frac{1}{2013}\right)=-\frac{1}{2010}+\frac{1}{2011}-\frac{1}{2012}+\frac{1}{2013}\)
\(A=-\frac{1}{2010.2011}-\frac{1}{2012.2013}\)
Vì 2010.2011 > 2009.2010 => \(\frac{1}{2010.2011}-\frac{1}{2009.2010}\)
\(-\frac{1}{2012.2013}>-\frac{1}{2011.2012}\)
=> A > B
2008/2008.2009 và 2009/2009.2010
2008/2008.2009 < 2009/2009.2010
k mk na <3
2008/ 2008 × 2009> 2009/ 2009 × 2010
Mình thề 100% CHUẨN KHÔNG CẦN CHỈNH☺
=>A:1/2=1/1x3+1/3x5+1/5x7+...+1/99x101
=>2a=1/2(2/1x3+2/3x5+...+2/99x101)
từ đây tự làm
\(A=\frac{1}{2.3}+\frac{1}{6.5}+\frac{1}{10.7}+...+\frac{1}{198.101}\)
\(\Rightarrow2A=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{99.101}\)
\(\Rightarrow2A=\frac{1}{2}\left(1-\frac{1}{101}\right)\)
\(\Rightarrow4A=\frac{100}{101}\)
\(\Leftrightarrow A=\frac{100}{101}.\frac{1}{4}=\frac{4.25}{101.4}=25< 26\)
#)Giải :
\(\frac{-5}{12}< \frac{a}{5}< \frac{1}{4}\Leftrightarrow\frac{-25}{60}< \frac{12a}{60}< \frac{15}{60}\Leftrightarrow-25< 12a< 15\)
\(\Leftrightarrow12a\in\left\{\pm12;-24\right\}\)
\(\Leftrightarrow a\in\left\{\pm1;2\right\}\)
Bài giải
Ta có :
\(-\frac{5}{12}< \frac{a}{5}< \frac{1}{4}\)
\(\Leftrightarrow\text{ }-\frac{25}{60}< \frac{12a}{60}< \frac{15}{60}\) \(\Rightarrow\text{ }-25< 12a< 15\)
\(\Rightarrow\text{ }-1,25< a< 1,25\)
\(\text{Do }a\in Z\text{ }\Rightarrow\text{ }x\in\left\{-1\text{ ; }0\text{ ; }1\right\}\)
\(P=\frac{2009.2010-1}{2009.2010}=\frac{2009.2010}{2009.2010}-\frac{1}{2009.2010}=1-\frac{1}{2009.2010}\)
\(Q=\frac{2010.2011-1}{2010.2011}=\frac{2010.2011}{2010.2011}-\frac{1}{2010.2011}=1-\frac{1}{2010.2011}\)
Vì \(\frac{1}{2009.2010}>\frac{1}{2010.2011}\)nên \(1-\frac{1}{2009.2010}< 1-\frac{1}{2010.2011}\)\(\Leftrightarrow\)\(P< Q\)
p<q nha