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Mình làm câu a) nha!!!
+) \(A=2009^{2010}+2009^{2009}\)
\(=2009^{2009}.\left(2009+1\right)\)
\(=2009^{2009}.2010\)
+) \(B=2010^{2010}=2010^{2009}.2010\)
Vì \(2010^{2009}>2009^{2009}\)nên \(2010^{2009}.2010>2009^{2009}.2010\)hay \(B>A\)
Vậy \(A< B\)
Hok tốt nha^^
ta có: \(A=\frac{2009^{10}+2}{2009^{11}+2}< 1\)
\(B=\frac{2009^{12}+2}{2009^{12}+2}=1\)
\(\Rightarrow A< B\)
\(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+.....+\frac{1}{80}\)
\(=\left(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+\frac{1}{44}+.....+\frac{1}{60}\right)+\left(\frac{1}{61}+\frac{1}{62}+......+\frac{1}{80}\right)\)
\(>\left(\frac{1}{60}+\frac{1}{60}+\frac{1}{60}+.....+\frac{1}{60}\right)+\left(\frac{1}{80}+\frac{1}{80}+\frac{1}{80}+.....+\frac{1}{80}\right)\)
\(=\frac{1}{3}+\frac{1}{4}\)
\(=\frac{7}{12}\)
\(B=\frac{2008+2009+2010}{2009+2010+2011}=\frac{2008}{2009+2010+2011}+\frac{2009}{2009+2010+2011}+\frac{2010}{2009+2010+2011}\)
\(< \frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}=A\)
Ta có :
�=20092010−220092011−2<1B=20092011−220092010−2<1
⇔�<20092010−2+201120092011−2+2011=20092010+200920092011+2009=2009(20092009+1)2009(20092010+1)=20092009+120092010+1=�⇔B<20092011−2+201120092010−2+2011=20092011+200920092010+2009=2009(20092010+1)2009(20092009+1)=20092010+120092009+1=A
⇔�>�⇔A>B