1/2.3 x + 1/3.4 x + 1/4.5 x + … + 1/4950 x = 1 60% + 0,4 x + x : 3 = 2

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1. Đáp án:

    

   Giải thích các bước giải:

   `1/2.3 x + 1/3.4 x + 1/4.5 x + …  + 1/49.50 x = 1`

   `x . (1/2.3 + 1/3.4 + 1/4.5 + … + 1/49.50) = 1`

   `x . (1/2 -1/3 + 1/3 – 1/4 + 1/4 – 1/5+  … + 1/49- 1/50) = 1`

   `x . (1/2 – 1/50) = 1`

   `x . 12/25 = 1`

   `x = 1 : 12/25`

   `x = 25/12 `

   vậy `x = 25/12 `

   `60% + 0,4 . x + x : 3 = 2`

   `3/5 + 7/5. x + x . 1/3 = 2`

   `3/5 + x . ( 7/5 + 1/3) = 2`

   `3/5 + x . 26/15 = 2`

   `x . 26/15 = 2 – 3/5`

   `x . 26/15 = 7/5`

   `x = 7/5  :26/15`

   `x = 21/6 `

   vậy `x = 21/6`

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2. `1/2.3 x + 1/3.4 x + 1/4.5 x + …  + 1/49.50 x = 1`

    `x . (1/2.3 + 1/3.4 + 1/4.5 + … + 1/49.50) = 1`

   `x . (1/2 -1/3 + 1/3 – 1/4 + 1/4 – 1/5+  … + 1/49- 1/50) = 1`

   `x . (1/2 – 1/50) = 1`

   `x . (25/50 – 1/50) = 1`

   `x . 12/25 = 1`

   `x = 1 : 12/25`

   `x = 25/12`

   ` – – – –  — – `

   `60% + 0,4 . x + x : 3 = 2`

   `3/5 + 7/5. x + x . 1/3 = 2`

   `3/5 + x . ( 7/5 + 1/3) = 2`

   `3/5 + x . (21/15 + 5/15) = 2`

   `3/5 + x . 26/15 = 2`

   `x . 26/15 = 2 – 3/5`

   `x . 26/15 = 10/5 -3/5`

   `x . 26/15 = 7/5`

   `x = 7/5  :26/15`

   `x =  21/6`

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