2 bài này Ngắn gọn nhưng đúng ạ!

Bài 33

`A=2/15 + 2/35 + 2/63+2/99+2/143`

`A=2/(3 . 5) + 2/(5 . 7) + 2/(7 . 9)+2/(9.11)+2/(11.13)`

`A=1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + 1/9 - 1/11 + 1/11 - 1/13`

`A=1/3 - 1/13`

`A=13/39 - 3/39`

`A=10/39`

 Bài 34

`A=1 + 3/15 + 3/35 + 3/63+...+3/9999`

`A= 3/3 + 3/(3 . 5) + 3/(5 . 7) + 3/(7 . 9)+...+3/(99.101)`

`A=3/2 . (2/(1 . 3) + 2/(3 . 5) + 2/(5 . 7) + 2/(7 . 9)+...+2/(99.101))`

`A=3/2 . (1 - 1/3 + 1/3 - 1/5 + ... + 1/99 - 1/101)`

`A=3/2 . (1 - 1/101)`

`A=3/2 . 100/101`

`A=150/101`

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