x+ 4/9.13 + 4/13.17 + 4//17.21 + …… + 4/41.45 = 10

0 bình luận về “x+ 4/9.13 + 4/13.17 + 4//17.21 + …… + 4/41.45 = 10”

1. Đáp án: $x=\dfrac{446}{45}$

    Giải thích các bước giải:

    $x+\dfrac{4}{9.13}+\dfrac{4}{13.17}+….+\dfrac{4}{41.45} = 10$

   $⇔x+\dfrac{1}{9}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{17}+….+\dfrac{1}{41}-\dfrac{1}{45} = 10$

   $⇔x+\dfrac{1}{9}-\dfrac{1}{45} = 10$

   $⇔x=\dfrac{446}{45}$

   Vậy $x=\dfrac{446}{45}$

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2. `x+ 4/(9.13) + 4/(13.17) + 4/(17.21) + …… + 4/(41.45) = 10`

   `=>x+ (4/(9.13) + 4/(13.17) + 4/(17.21) + …… + 4/(41.45) )= 10`

   `=>x+ (1/9-1/13 + 1/13-1/17 + 1/17-1/21 + …… + 1/41-1/45 )= 10`

   `=>x+ (1/9-1/45 )= 10`

   `=>x+ 4/45= 10`

   `=>x=9 41/45`

   Học tốt!!!

   #nocopy

    

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