Question

Tính C = \(\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{98.99.100}\)

Answer 1

cách làm như sau

\(C=\frac{2}{2}.\left[\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+....+\frac{1}{98.99}-\frac{1}{99.100}\right]\)

\(C=1\left[\frac{1}{2}-\frac{1}{9900}\right]\)

\(C=\frac{4949}{9900}\)

Answer 2

cần làm ra ko

Answer 3

CÓ CHỨ

Answer 4

\(C=\frac{1}{2}\left(\frac{1}{1x2}-\frac{1}{2x3}\right)+\frac{1}{2}\left(\frac{1}{2x3}-\frac{1}{3x4}\right)+.........................+\frac{1}{2}\left(\frac{1}{98x99}-\frac{1}{99x100}\right).\)

    \(=\frac{1}{2}\left(\frac{1}{1x2}-\frac{1}{2x3}+\frac{1}{2x3}-\frac{1}{3x4}+\frac{1}{3x4}-\frac{1}{4x5}+...................+\frac{1}{89x99}-\frac{1}{99x100}\right)\)

    \(=\frac{1}{2}\left(\frac{1}{2}-\frac{1}{99x100}\right)\)

    \(=\frac{1}{2}x\frac{4949}{9900}=\frac{4949}{19800}\)

vậy \(C=\frac{4949}{19800}\)

Answer 5

sai zùi bn ơi tôi làm như bn có mà ăn vả ko thôi đó