Question

\(A=\frac{2}{4.7} +\frac{2}{7.10}+\frac{2}{10.13}+...+\frac{2}{73.76}\)

Answer 1

các bn trả lời nhanh nhé

đến 9:10 nhé

Answer 2

\(A=\frac{2}{4.7}+\frac{2}{7.10}+\frac{2}{10.13}+.....+\frac{2}{73.76}\)

\(=\frac{2}{3}\left(\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+....+\frac{3}{73.76}\right)\)

\(=\frac{2}{3}\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+....+\frac{1}{73}-\frac{1}{76}\right)\)

\(=\frac{2}{3}\left(\frac{1}{4}-\frac{1}{76}\right)\)

\(=\frac{2}{3}.\frac{9}{38}=\frac{3}{19}\)

Answer 3

A=\(\frac{3}{3}\cdot\left(\frac{2}{4\cdot7}+\frac{2}{7\cdot10}+\frac{2}{10\cdot13}+...+\frac{2}{73\cdot76}\right)\)

A=\(\frac{1}{3}\cdot3\cdot\left(\frac{2}{4\cdot7}+\frac{2}{7\cdot10}+\frac{2}{10\cdot13}+...+\frac{2}{73\cdot76}\right)\)

A=\(\frac{1}{3}\cdot\left(\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+\frac{3}{10\cdot17}+...+\frac{3}{73\cdot76}\right)\)

A=\(\frac{1}{3}\cdot\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}-\frac{1}{13}+...+\frac{1}{73}-\frac{1}{76}\right)\)

A=\(\frac{1}{3}\cdot\left(\frac{1}{4}-\frac{1}{76}\right)\)

A=\(\frac{1}{3}\cdot\left(\frac{19}{76}-\frac{1}{76}\right)\)

A=\(\frac{1}{3}\cdot\frac{18}{76}\)

A=\(\frac{1\cdot6}{1\cdot76}\)

A=\(\frac{6}{76}\)

chúc bạn một ngày tốt lành