Câu hỏi của Tiếng anh123456

Question

large_1694528904482.jpg (1024×1280)

Làm ý b thôi nhé

Nguyễn Lê Phước Thịnh · Accepted Answer

b: $=\dfrac{9}{2}\left(\dfrac{2}{2\cdot4}+\dfrac{2}{4\cdot6}+...+\dfrac{2}{98\cdot100}\right)$

$=\dfrac{9}{2}\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+...+\dfrac{1}{98}-\dfrac{1}{100}\right)$

$=\dfrac{9}{2}\cdot\dfrac{49}{100}=\dfrac{441}{200}$

Câu trả lời:

b: $=\dfrac{9}{2}\left(\dfrac{2}{2\cdot4}+\dfrac{2}{4\cdot6}+...+\dfrac{2}{98\cdot100}\right)$

$=\dfrac{9}{2}\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+...+\dfrac{1}{98}-\dfrac{1}{100}\right)$

$=\dfrac{9}{2}\cdot\dfrac{49}{100}=\dfrac{441}{200}$