D= ( 1/2 – 1 ) . ( 1/3 – 1 ) . ( 1/4 – 1 ). ….( 1/2009 – 1)

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1. `D= ( 1/2 – 1 ) . ( 1/3 – 1 ) . ( 1/4 – 1 ). ….( 1/2009 – 1)`

   `D= -1/2 . -2/3 . -3/4 … -2008/2009`

   `D= -(1/2 . 2/3 . 3/4 … 2008/2009)`

   `D= -1/2009`

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2. Đáp án:

    

   Giải thích các bước giải:

   `D = (1/2 – 1) . (1/3 – 1) . (1/4 – 1) …(1/2009 – 1)`

   `D = (1/2 – 2/2) . (1/3 – 3/3) . (1/4 – 4/4) … (1/2009 – 2009/2009)`

   `D = -1/2 .-2/3 . -3/4 … -2008/2009`

   `D = [(-1) . (-2) . (-3) … (-2008)]/(1 . 2 . 3 … 2009)`

   `D = 1/2009`

   Học tốt. Nocopy.

    

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