Question

\(\frac{1}{1\cdot2}+\frac{1}{3\cdot4}+\frac{1}{5\cdot6}+...+\frac{1}{49\cdot50}\)

Answer 1

Ta thấy:1/1.2 =1−1/2 ,1/2.3 =1/2 −1/3 ,...,1/49.50 =1/49 −1/50 

=>A=1/1.2 +1/2.3 +1/3.4 +...+1/49.50 

=>A=1−1/2 +1/2 −1/3 +1/3 −1/4 +...+1/49 −1/50 

=>A=1−1/50 

=>A=49/50 

Answer 2

Cảm ơn bạn nhé nhưng đâu có 1/2*3 đâu?