\(C=\frac{1}{100}-\left(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\right)\)

Đặt E = \(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-...-\frac{1}{100}=\frac{99}{100}\)

\(50C=\left(\frac{1}{100}-\frac{99}{100}\right).5-=-\frac{49}{50}.50=-49\)

-49

mình giải rồi vòng 11 đó 

\(C=\frac{1}{100}-\left(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{98.99}+\frac{1}{99.100}\right)\)

\(=\frac{1}{100}-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\right)\)

\(=\frac{1}{100}-\left(1-\frac{1}{100}\right)\)

\(=\frac{1}{100}-\frac{99}{100}=-\frac{49}{50}\)

=> 50C = \(50.\left(-\frac{49}{50}\right)=-49\)

-49 đúng thì cho một lần ****

C=-49/50

=>50C=-49

 Cách giải dài lắm

\(C=\frac{1}{100}-\left(\frac{1}{100\cdot99}+\frac{1}{99\cdot98}+\cdot\cdot\cdot+\frac{1}{2\cdot1}\right)\)

\(C=\frac{1}{100}-\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\cdot\cdot\cdot+\frac{1}{98\cdot99}+\frac{1}{99\cdot100}\right)\)

\(C=\frac{1}{100}-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\cdot\cdot\cdot+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\right)\)

\(C=\frac{1}{100}-\left(1-\frac{1}{100}\right)\)

\(C=\frac{1}{100}-\left(\frac{100}{100}-\frac{1}{100}\right)\)

\(C=\frac{1}{100}-\frac{99}{100}\)

\(C=\frac{-98}{100}\)

\(Khi\) đó \(50C=\frac{-98}{100}\cdot50\)

\(50C=-49\)

tick cho mình nha

C = \(\frac{1}{100}-\left(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{98.99}+\frac{1}{99.100}\right)\)

\(=\frac{1}{100}-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\right)\)

\(=\frac{1}{100}-\left(1-\frac{1}{100}\right)\)

\(=\frac{1}{100}-\frac{99}{100}=-\frac{49}{50}\)

\(\Rightarrow50C=50.\left(-\frac{49}{50}\right)=-49\)

mk moi giai violympic =50 sao đó

mk nghi z

mk thi co 10 cau mk cung giai cau do nhung co dc 90 diem o

ma mk nghi chac cau do dung

Đặt A=  \(-\frac{1}{100.99}-\frac{1}{99.98}-....-\frac{1}{2.1}=-\left(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\right)\)

\(A=-\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-...-\frac{1}{100}\right)=-\left(1-\frac{1}{100}\right)=-\frac{99}{100}\)

C = \(\frac{1}{100}+\left(-\frac{99}{100}\right)=-\frac{49}{50}\)

50C = \(-\frac{49}{50}.50=-49\)

C=-49/50

=>50C=-49

cách giải dài lắm

cách giai như thế nào

???????

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