\(B=\frac{\frac{1}{39}-\frac{1}{6}-\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}:\frac{31}{6}\)

\(=\frac{\frac{1}{3}\left(\frac{1}{13}-\frac{1}{2}-\frac{1}{17}\right)}{\frac{1}{4}\left(\frac{1}{2}-\frac{1}{13}+\frac{1}{17}\right)}.\frac{6}{31}\)

\(=\frac{\frac{-1}{3}\left(\frac{-1}{13}+\frac{1}{2}+\frac{1}{17}\right)}{\frac{1}{4}\left(\frac{1}{2}-\frac{1}{13}+\frac{1}{17}\right)}.\frac{6}{31}\)

\(=\frac{-1}{3}:\frac{1}{4}.\frac{6}{31}\)

\(=\frac{-1}{3}.4.\frac{6}{31}\)

Tiếp theo dễ r tự làm tiếp :)

Ta có: \(\frac{\frac{1}{6}-\frac{1}{39}+\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}=\frac{\left(\frac{1}{6}-\frac{1}{39}+\frac{1}{51}\right).5304}{\left(\frac{1}{8}-\frac{1}{52}+\frac{1}{68}\right).5304}\)\(=\frac{136-884+104}{663-102+78}=-\frac{664}{639}\)

Ta có : \(\frac{\frac{1}{39}-\frac{1}{6}-\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}=\frac{\left(\frac{1}{39}-\frac{1}{6}-\frac{1}{51}\right)\times5304}{\left(\frac{1}{8}-\frac{1}{52}+\frac{1}{68}\right)\times5304}=\frac{136-884-104}{663-102+78}=\frac{-852}{639}=-\frac{4}{3}\)

\(\frac{-4}{3}\)

\(\text{Đặt }A=\frac{\frac{1}{6}+\frac{1}{51}+\frac{1}{39}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}\)

\(\Rightarrow\frac{1}{A}=\frac{6+51+39}{8-52+68}=4\)

\(\text{Vậy }A=\frac{1}{4}\)

Xét : 1/8 - 1/52 + 1/68

= 3/4 . 1/6 - 3/4 . 1/39 + 3/4 . 1/68

= 3/4 . (1/6-1/39+1/51)

=> E = 1/(3/4) = 4/3

Tk mk nha

\(\text{E}=\frac{\frac{1}{6}-\frac{1}{39}+\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}\)

\(\text{E}=\frac{\frac{1}{6}-\frac{1}{39}+\frac{1}{51}}{\frac{3}{4}.\frac{1}{6}-\frac{3}{4}.\frac{1}{39}+\frac{3}{4}.\frac{1}{68}}\)

\(\text{E}=\frac{\frac{1}{6}-\frac{1}{39}+\frac{1}{51}}{\frac{3}{4}\left(\frac{1}{6}-\frac{1}{39}+\frac{1}{51}\right)}\)

\(\text{E}=\frac{1}{\left(\frac{3}{4}\right)}=\frac{4}{3}\)

Ta có : \(B=\frac{\frac{1}{39}-\frac{1}{6}-\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}:5\frac{1}{6}\)

=> \(B=\frac{\frac{\frac{1}{13}-\frac{1}{2}-\frac{1}{17}}{3}}{\frac{\frac{1}{2}-\frac{1}{13}+\frac{1}{17}}{4}}:5\frac{1}{6}\)

=> \(B=\frac{\frac{\frac{1}{13}-\frac{1}{2}-\frac{1}{17}}{3}}{\frac{\frac{1}{13}-\frac{1}{2}-\frac{1}{17}}{-4}}:5\frac{1}{6}\)

=> \(B=\frac{-4}{3}:5\frac{1}{6}\)

=> \(B=\frac{-8}{6}:\frac{31}{6}=-\frac{8}{6}.\frac{6}{31}=-\frac{8}{31}\)

Nguyễn Ngọc Lộc No choice teenPhạm Thị Diệu HuyềnTrên con đường thành công không có dấu chân của kẻ lười biếngVũ Minh Tuấn

\(=\frac{\frac{1}{3}.\left(\frac{1}{2}-\frac{1}{13}+\frac{1}{17}\right)}{\frac{1}{4}.\left(\frac{1}{2}-\frac{1}{13}+\frac{1}{17}\right)}=\frac{4}{3}\)

\(\frac{\frac{1}{6}-\frac{1}{39}+\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}=\frac{\frac{1}{3}.\left(\frac{1}{2}-\frac{1}{13}+\frac{1}{17}\right)}{\frac{1}{4}.\left(\frac{1}{2}-\frac{1}{13}+\frac{1}{17}\right)}=\frac{4}{3}\)

A=\(-\frac{2392}{19809}\)

đẹp tk nha