Question

[kieu the bao]

\(A=\frac{7}{3.13}+\frac{7}{13.23}+\frac{7}{23.33}+.......+\frac{7}{53.63}\)

ƯU TIÊN DƯỚI 25 NHÁ

Answer 1

[kudo shinichi]

\(A=\frac{7}{3.13}+\frac{7}{13.23}+...+\frac{7}{53.63}\)

\(A=7.\left(\frac{1}{3.13}+\frac{1}{13.23}+...+\frac{1}{53.63}\right)\)

\(10A=7.\left(\frac{10}{3.13}+\frac{10}{13.23}+...+\frac{10}{53.63}\right)\)

\(10A=7.\left(\frac{1}{3}-\frac{1}{63}\right)\)

\(10A=7.\frac{20}{63}\)

\(10A=\frac{20}{9}\)

\(A=\frac{20}{9}:10\)

\(A=\frac{20}{9}.\frac{1}{10}\)

\(A=\frac{2}{9}\)

Vậy A=\(\frac{2}{9}\)

Chúc bạn học tốt~

Answer 2

[Nguyễn Tuấn Bách]

A = \(\frac{7}{3.13}\)\(+\)\(\frac{7}{13.23}\)\(+\)\(\frac{7}{23.33}\)\(+\)..........  \(+\)\(\frac{7}{53.63}\)

\(\Rightarrow\)A = 7 . (\(\frac{1}{3.13}\)\(+\)\(\frac{1}{13.23}\)\(+\)\(\frac{1}{23.33}\)\(+\)...... \(\frac{1}{53.63}\))

\(\Rightarrow\)A = \(\frac{1}{10}\). 7 . ( \(\frac{1}{3}\)\(-\)\(\frac{1}{13}\)\(+\)\(\frac{1}{13}\)\(-\)\(\frac{1}{23}\)\(+\)\(\frac{1}{23}\)\(-\)\(\frac{1}{33}\)\(+\)....... \(+\)\(\frac{1}{53}\)\(-\)\(\frac{1}{63}\))

\(\Rightarrow\)A = \(\frac{7}{10}\). ( \(\frac{1}{3}\)\(-\)\(\frac{1}{63}\))

\(\Rightarrow\)A = \(\frac{7}{10}\). \(\frac{20}{63}\)

\(\Rightarrow\)A = \(\frac{2}{9}\)

Chúc các anh em học tốt !!!