Question

Tìm A

A= 5/1.2 + 5/2.3 + ...+ 5/99.100

 

Answer 1

A = 5 .(1/1.2 +1/2.3 + 1/3.4 +.....1/99.100)

A= 5 . (1/1 - 1/2 +1/2 -1/3 +1/3 -1/4 ........ +1/99 - 1/100)

A= 5 . (1/1 - 1/100)

A= 5.99/100 

A= 99/20

Answer 2

A=5.(1-1/2+1/2-1/3 + .... + 1/99 - 1/100)

  = 5.(1-1/100)

  =5 . 99/100

  = 99/20

Answer 3

Đáp số: 99/20

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