Question

6/1*3 + 6/ 3* 5 + 6 / 5*7 + ... + 6/ 49* 51 

Ai giúp tớ làm bài này với

Answer 1

\(\frac{6}{1.3}+\frac{6}{3.5}+\frac{6}{5.7}+...+\frac{6}{49.51}\)

\(=3\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{49.51}\right)\)

\(=3\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{49}-\frac{1}{51}\right)\)

\(=3\left(1-\frac{1}{51}\right)\)

\(=3.\frac{50}{51}\)

Chúc bn hok tốt

Answer 2

\(\frac{6}{1\cdot3}+\frac{6}{3\cdot5}+\frac{6}{5\cdot7}+...+\frac{6}{49\cdot51}\)

\(=3\left(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+...+\frac{2}{49\cdot51}\right)\)

\(=3\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{49}-\frac{1}{51}\right)\)

\(=3\left(1-\frac{1}{51}\right)\)

\(=3\cdot\frac{50}{51}\)

\(=\frac{50}{17}\)

Answer 3

Đặt \(A=\frac{6}{1.3}+\frac{6}{3.5}+\frac{6}{5.7}+.........+\frac{6}{49.51}\)

\(A=\frac{6}{1.3}+\frac{6}{3.5}+\frac{6}{5.7}+........+\frac{6}{49.51}\)

\(=6\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+..........+\frac{1}{49.51}\right)\)

\(=\left(6.\frac{1}{2}\right)\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+........+\frac{2}{49.51}\right)\)

\(=3\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-........-\frac{1}{51}\right)\)

\(=3\left(1-\frac{1}{51}\right)\)

\(=3\left(\frac{51}{51}-\frac{1}{51}\right)\)

\(=3.\frac{50}{51}\)

\(=\frac{150}{51}\)

Vậy \(A=\frac{150}{51}\)

Answer 4

\(\frac{6}{1.3}+\frac{6}{3.5}+\frac{6}{5.7}+...+\frac{6}{49.51}\)

\(=\frac{6}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{49.51}\right)\)

\(=3.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{49}-\frac{1}{51}\right)\)

\(=3.\left(1-\frac{1}{51}\right)\)

\(=3.\frac{50}{51}\)

\(=\frac{50}{17}\)

_Chúc bạn học tốt_

Answer 5

Rút gọn thành \(\frac{50}{17}\)nha

Mình quên chưa rút gọn

Answer 6

50/17