-My idol is Truong Han. He 's Chinese. He is an actor. He look so handsome.And i love he 4ever!! But not much.

- Thần tượng của mình là Trương Hàn. Anh ấy là người Trung Quốc. Anh ấy là một diễn viên. Anh ấy nhìn thật đẹp trai. Tôi yêu anh ấy mãi mãi!!! Nhưng không nhiều lắm.

Ta có: \(\dfrac{20}{39}>\dfrac{20}{41}>\dfrac{18}{41}\left(1\right)\)

\(\dfrac{22}{27}>\dfrac{22}{29}\left(2\right)\)

\(\dfrac{18}{43}=1-\dfrac{25}{43};\dfrac{14}{39}=1-\dfrac{25}{39}\)

Vì \(\dfrac{25}{43}< \dfrac{25}{39}\Rightarrow1-\dfrac{25}{43}>1-\dfrac{25}{39}\Rightarrow\dfrac{18}{43}>\dfrac{14}{39}\left(3\right)\)

Từ \(\left(1\right);\left(2\right);\left(3\right)\) ta suy ra : A>B

101 quả

\(2005A=\dfrac{2005.\left(2005^{2014}+1\right)}{2005^{2015}+1}=\dfrac{2005^{2015}+2005}{2005^{2015}+1}\)

\(2005A=\dfrac{2005^{2015}+1+2004}{2005^{2015}+1}=1+\dfrac{2004}{2005^{2015}+1}\)

\(2005B=\dfrac{2005.\left(2005^{2015}+1\right)}{2005^{2016}+1}=\dfrac{2005^{2016}+2005}{2005^{2016}+1}\)

\(2005B=\dfrac{2005^{2016}+1+2004}{2005^{2016}+1}=1+\dfrac{2004}{2005^{2016}+1}\)

Vì \(\dfrac{2004}{2005^{2015}+1}>\dfrac{2004}{2005^{2016}+1}\Rightarrow1+\dfrac{2004}{2005^{2016}+1}>\dfrac{2004}{2005^{2016}+1}\)

\(\Rightarrow10A>10B\Rightarrow A>B\)

nhìu thế giảm tải dc ko                  

\(C=\dfrac{3}{4.7}+\dfrac{3}{7.10}+...+\dfrac{3}{36.39}=\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+...+\dfrac{1}{36}-\dfrac{1}{39}\)

\(C=\dfrac{1}{4}-\dfrac{1}{36}=\dfrac{9}{36}-\dfrac{1}{36}=\dfrac{8}{36}=\dfrac{4}{18}\)