Question

A=\(\frac{3}{5.7}+\frac{3}{7.9}+.....+\frac{3}{59.61}\)=?

 

Answer 1

\(\frac{2}{3}A=\frac{2}{3}.\left(\frac{3}{5.7}+\frac{3}{7.9}+...+\frac{3}{59.61}\right)\)

\(\frac{2}{3}A=\frac{2.3}{3.5.7}+\frac{2.3}{3.7.9}+...+\frac{2.3}{3.59.61}\)

\(\frac{2}{3}A=\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{59.61}\)

\(\frac{2}{3}A=\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{59}-\frac{1}{61}\)

\(\frac{2}{3}A=\frac{1}{5}-\frac{1}{61}\)

\(\frac{2}{3}A=\frac{56}{305}\)

\(A=\frac{56}{305}.\frac{3}{2}\)

\(A=\frac{84}{305}\)

Answer 2

dễ ợt

A= 1/5-1/61= 56/305

Answer 3

\(A=\frac{3}{5.7}+\frac{3}{7.9}+...+\frac{3}{59.61}\)

\(A=\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{3}{59.61}\)

\(A=\frac{1}{5}-\frac{1}{61}\)

\(A=\frac{56}{305}\)

Answer 4

56/305

Answer 5

A=3/2 . (2/5.7 + 2/7.9 +...+2/59.61)

A=3/2 . (1/5-1/7+1/7-1/9+...+1/59-1/61)

A=3/2 . (1/5-1/61)

A=3/2 . 56/305

A=84/305

Answer 6

A=3/2 . (2/5.7 + 2/7.9 +...+2/59.61)

A=3/2 . (1/5 -1/7 + 1/7 - 1/9 +...+ 1/59 - 1/61)

A=3/2 . (1/5 - 1/61)

A=3/2 . 56/305

A=84/305

Answer 7

\(A=\frac{3}{5\cdot7}+\frac{3}{7\cdot9}+....+\frac{3}{59\cdot61}\)

\(\frac{2}{3}A=\frac{2}{5\cdot7}+\frac{2}{7\cdot9}+....+\frac{2}{59\cdot61}\)

\(\frac{2}{3}A=\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+....+\frac{1}{59}-\frac{1}{61}\)

\(\frac{2}{3}A=\frac{1}{5}-\frac{1}{61}=\frac{56}{305}\)

\(A=\frac{56}{305}:\frac{2}{3}\)

Answer 8

56/305