Question

A=1/1x2+1/2x3+1/3x4+.....+1/49x50

Answer 1

Ta có : 

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

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

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

\(A=\frac{49}{50}\)

Vậy \(A=\frac{49}{50}\)

Chúc bạn học tốt ~ 

Answer 2

= 1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/49 - 1/50

= 1/1 - 1/50

= 49/50
 

Answer 3

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

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

\(=1-\frac{1}{50}=\frac{49}{50}\)

k mk nha

thanks

Answer 4

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

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

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

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

\(A=\frac{49}{50}\)

Chúc bạn học tốt !!! 

Answer 5

A=1/1.2+1/2.3+...+1/49.50

=>A=1-1/2+1/2-1/3+...+1/49-1/50

=>A=1-1/50=49/50

P/S:dấu chấm là dấu nhân nha

Answer 6

cam on moi nguoi nha

Answer 7

A=1/1x2+1/2x3+1/3x4+....+1/49x50

  =1/1-1/2+1/2-1/3+1/3-1/4+...+1/49-1/50

   =1/1-1/50

   =49/50