50/51

dap an da dung roi

cách giải thế nào rồi mình an tick cho

A=\(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+...+\frac{1}{50\cdot51}\)

A=\(\left(\frac{1}{1}-\frac{1}{2}\right)+\left(\frac{1}{2}-\frac{1}{3}\right)+...+\left(\frac{1}{50}-\frac{1}{51}\right)\)

A=\(1-\frac{1}{51}\)

A=\(\frac{50}{51}\)

50/51

50/51

A = 1/2 + 1/6 + 1/12 + ..... + 1/2550

A = 1/1.2 + 1/2.3 + ....... + 1/50.51

A = 1/1 - 1/2 + 1/2 - .......  - 1/51

A=  1 - 1/51 = 50/51 

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{2450}+\frac{1}{2550}\)

\(A=\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{49x50}+\frac{1}{50x51}\)

\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{49}-\frac{1}{50}+\frac{1}{50}-\frac{1}{51}\)

\(A=1-\frac{1}{51}=\frac{50}{51}\)

50/51

49/303

Đúng 100% nhé cô mình mới dạy xong !

các bạn hướng dẫn cách làm cụ thể được không

50/51

A = \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...........+\frac{1}{49.50}+\frac{1}{50.51}\)

   = \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-........+\frac{1}{49}-\frac{1}{50}+\frac{1}{50}-\frac{1}{51}\)

   = \(1-\frac{1}{51}=\frac{50}{51}\)