\(A=1+\frac{2}{6}+\frac{2}{12}+...+\frac{2}{9702}+\frac{2}{9900}=1+\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{98.99}+\frac{2}{99.100}\)
=> \(A=1+2\left(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{98.99}+\frac{1}{99.100}\right)\)
\(A=1+2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\right)\)
\(A=1+2\left(\frac{1}{2}-\frac{1}{100}\right)=1+2.\frac{49}{100}=1+\frac{49}{50}=\frac{99}{50}\)
Đáp số: \(A=\frac{99}{50}\)
A=2/2+2/6+2/12+...+2/9900
A=2(1/1.2+1/2.3+1/3.4+...+1/99.100)
A=2(1-1/2+1/2-1/3+1/3-1/4+.....+1/99-1/100)
A=2(1-1/100)
A=2.99/100
A=99/55
Vậy A=99/55
bùi thế hào à , cậu lam vay làm gì cho mất công!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1
