Question

Tính

1/1.3+1/3.5+1/5.7+......+1/253.255+ 1/255.257

Answer 1

1/1.3+...+1/255.257

=> 1/2.(1/1-1/3+1/3-1/5+...+1/255-1/257)

=> 1/2.(1/1-1/257)

=> 1/2.256/257

=> 128/257

Answer 2

ai giúp tôi với

Answer 3

\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{253.255}+\frac{1}{255.257}\)

\(=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{253.255}+\frac{2}{255.257}\)

\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{255}-\frac{1}{257}\)

\(=1-\frac{1}{257}\)

\(=\frac{256}{257}\)

Answer 4

cảm ơn các bạn nhìu