\(C=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{\frac{5}{2008}-\frac{5}{2009}-\frac{5}{2010}}+\frac{\frac{2}{2007}-\frac{2}{2008}-\frac{2}{2009}}{\frac{3}{2007}-\frac{3}{2008}-\frac{3}{2009}}\)

\(=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{5.\left(\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}\right)}+\frac{2.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}{3.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}\)

\(=\frac{1}{5}+\frac{2}{3}\)

\(=\frac{13}{15}\)

       2007/2008 x 1/2009 + 2007/2008 : 2009/2008 + 1/2008

= 2007/2008 x 1/2009 + 2007/2008 x 2008/2009 + 1/2008

= 2007/2008 x (1/2009 + 2008/2009) + 1/2008

= 2007/2008 x 1 + 1/2008

= 2007/2008 + 1/2008

= 2008/2008 = 1

\(=\left(\frac{2007}{2008}+\frac{1}{2008}\right)+\left(\frac{2007}{2008}.\frac{2008}{2009}+\frac{1}{2009}\right)\)

\(=1+\frac{2008}{2009}=\frac{4017}{2009}\)

\(\frac{2007}{2008}+\frac{1}{2009}+\frac{2007}{2008}:\frac{2009}{2008}+\frac{1}{2008}\)

\(=\frac{2007}{2008}+\frac{1}{2009}+\frac{2007}{2009}+\frac{1}{2008}\)

\(=\left(\frac{2007}{2008}+\frac{1}{2008}\right)+\left(\frac{2007}{2009}+\frac{1}{2009}\right)\)

\(=1+\frac{2008}{2009}\)

\(=\frac{4017}{2009}\)

a-b+c+d=\(\frac{2008}{2009}-\frac{2009}{2008}+\frac{1}{2009}+\frac{2007}{2008}=\left(\frac{2008}{2009}+\frac{1}{2009}\right)-\left(\frac{2009}{2008}-\frac{2007}{2008}\right)=1-\frac{2}{2008}=\frac{2006}{2008}=\frac{1003}{1004}\)

\(a-b+c+d=\frac{2008}{2009}-\frac{2009}{2008}+\frac{1}{2009}+\frac{2007}{2008}\)

\(=\left(\frac{2008}{2009}+\frac{1}{2009}\right)+\left(\frac{2007}{2008}-\frac{2009}{2008}\right)=\frac{2009}{2009}+\frac{-2}{2008}\)

\(=1+\frac{-1}{1004}=\frac{1004}{1004}+\frac{-1}{1004}=\frac{1003}{1004}\)

\(a+b+c+d=\frac{2008}{2009}+\frac{2009}{2008}+\frac{1}{2009}+\frac{2007}{2008}\\ =\frac{2009}{2009}+\frac{4016}{2008}=1+2=3\)

\(\frac{2007}{2008}\)\(+\)\(\frac{2008}{2009}\)\(=\)\(\frac{2007}{2008}\)\(+\)\(\frac{2008}{2009}\)

k mk nha!!! *o~

\(\frac{2007}{2008}+\frac{2008}{2009}=\frac{2007}{2008}+\frac{2008}{2009}\)

nha                                                        ^_^

Mọi người giúp mjk cách lm nữa nhé 

Thank moj ng nhìu

tôi thích hoa hồng sai kìa

Vì 2006/2007 ; 2007/2008 ; 2008/2009 ; 2009/2010 đều bé hơn 1 nên:

2006/2007 + 2007/2008 + 2008/2009 + 2009/2010 < 1 + 1 + 1 + 1 = 4.

Vậy ...

A=\(\frac{2006}{2007}+\frac{2007}{2008}+\frac{2008}{2009}+\frac{2009}{2006}\)=3-(\(\frac{1}{2007}+\frac{1}{2008}+\frac{1}{2009}\))+1+\(\frac{3}{2006}\)=4+(\(\frac{1}{2006}-\frac{1}{2007}\))+(\(\frac{1}{2006}-\frac{1}{2008}+\frac{1}{2009}\))

=> A>4 (\(\frac{1}{2006}>\frac{1}{2007}>\frac{1}{2008}>\frac{1}{2009}\))