Cho a = 2008/2009 ; b = 2009/2008; c = 1/2009 ; d = 2007/2008. Tính a – b + c+ d

0 bình luận về “Cho a = 2008/2009 ; b = 2009/2008; c = 1/2009 ; d = 2007/2008. Tính a – b + c+ d”

1. Đáp án:

   `1003/1004`

   Giải thích các bước giải:

    `a-b+c+d=2008/2009-2009/2008+1/2009+2007/2008`

   `=(2008/2009+1/2009)+(2007/2008-2009/2008)`

   `=2009/2009-2/2008`

   `=1-1/1004`

   `=\frac{1004-1}{1004}`

   `=1003/1004`

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2. $\begin{array}{l}a-b+c+d\\=\dfrac{2008}{2009}-\dfrac{2009}{2008}+\dfrac1{2009}+\dfrac{2007}{2008}\\=\left(\dfrac{2008}{2009}+\dfrac1{2009}\right)+\left(-\dfrac{2009}{2008}+\dfrac{2007}{2008}\right)\\=1-\dfrac1{1004}\\=\dfrac{1003}{1004} \end{array}$

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