\(A=\frac{7}{3.13}+\frac{7}{13.23}+...+\frac{7}{53.63}\)
\(A=7.\left(\frac{1}{3.13}+\frac{1}{13.23}+...+\frac{1}{53.63}\right)\)
\(10A=7.\left(\frac{10}{3.13}+\frac{10}{13.23}+...+\frac{10}{53.63}\right)\)
\(10A=7.\left(\frac{1}{3}-\frac{1}{63}\right)\)
\(10A=7.\frac{20}{63}\)
\(10A=\frac{20}{9}\)
\(A=\frac{20}{9}:10\)
\(A=\frac{20}{9}.\frac{1}{10}\)
\(A=\frac{2}{9}\)
Vậy A=\(\frac{2}{9}\)
Chúc bạn học tốt~
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 !!!
A=1/3-1/13+1/13-1/23+1/23-1/33+.........+1/53-1/63
=1/3-1/63
=21/63-1/63
=20/63
