Question

[ 1 - 2/5 ] x [ 1 - 2/7 ] x [ 1 - 2/9 ] x [ 1 - 2/11 ] x ...... x [ 1 - 2/97 ] x [ 1 - 2/ 99 ] = 

Giúp tớ nhanh nha cânf gấp

 

 

Answer 1

#)Giải :

\(\left(1-\frac{2}{5}\right)\left(1-\frac{2}{7}\right)\left(1-\frac{2}{9}\right)...\left(1-\frac{2}{97}\right)\left(1-\frac{2}{99}\right)\)

\(=\frac{3}{5}\times\frac{5}{7}\times\frac{7}{9}\times...\times\frac{95}{97}\times\frac{97}{99}\)

\(=\frac{3}{99}=\frac{1}{33}\)( loại các cặp số giống nhau ở tử và mẫu của các phân số )

Answer 2

\(\left[1-\frac{2}{5}\right]\times\left[1-\frac{2}{7}\right]\times\left[1-\frac{2}{9}\right]\times\left[1-\frac{2}{11}\right]\times...\times\left[1-\frac{2}{97}\right]\times\left[1-\frac{2}{99}\right]\)

\(=\frac{3}{5}\times\frac{5}{7}\times\frac{7}{9}\times\frac{9}{11}\times...\times\frac{95}{97}\times\frac{97}{99}\)

\(=\frac{3\times5\times7\times9\times...\times97}{5\times7\times9\times11\times...\times97\times99}=\frac{3}{99}=\frac{1}{33}\)

Answer 3

\(\left[1-\frac{2}{5}\right]\times\left[1-\frac{2}{7}\right]\times\left[1-\frac{2}{9}\right]\times...\times\left[1-\frac{2}{97}\right]\times\left[1-\frac{2}{99}\right]\)

=\(\frac{3}{5}\times\frac{5}{7}\times\frac{7}{9}\times...\times\frac{95}{97}\times\frac{97}{99}\)

=\(\frac{3\times5\times7\times...95\times97}{5\times7\times9\times...\times97\times99}\)

=\(\frac{3}{99}\)

=\(\frac{1}{33}\)