so sanh 2009^2010+2009^2009 vs 2010^2010.
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Dễ thấy:
\(\frac{2008}{2009}>\frac{2008}{2009+2010+2011}\)
\(\frac{2009}{2010}>\frac{2009}{2009+2010+2011}\)
\(\frac{2010}{2011}>\frac{2010}{2009+2010+2011}\)
=>\(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}>\frac{2008}{2009+2010+2011}+\frac{2009}{2009+2010+2011}+\frac{2010}{2009+2010+2011}\)
Hay \(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}>\frac{2008+2009+2010}{2009+2010+2011}\)
Vậy A > B
20092010+20092009
=20092009.2009+20092009
=20092009(2009+1)
=20092009.2010
Mà 20102010=20102009.2010
nên 20092010+20092009 < 20102010
Xong rồi đó bạn
So sánh hai phân số :
\(\frac{2009.2009+2008}{2009.2009+2009}\)và \(\frac{2009.2009+2009}{2009.2009+2010}\)
\(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}+\frac{2011}{2008}=1-\frac{1}{2009}+1-\frac{1}{2010}+1-\frac{1}{2011}+1+\frac{3}{2008}\)
\(=4+\left(\frac{1}{2008}-\frac{1}{2009}\right)+\left(\frac{1}{2008}-\frac{1}{2010}\right)+\left(\frac{1}{2008}-\frac{1}{2011}\right)>4\)