a) 3/4x – 1/4= 2(x – 3)+1/4 b) 30℅x-x+5/6=49/2

0 bình luận về “a) 3/4x – 1/4= 2(x – 3)+1/4 b) 30℅x-x+5/6=49/2”

1. Đáp án:

    `a//` `x=22/5`

   `b//` `x=(-710)/21`

   Giải thích các bước giải:

   `a)` `3/4x – 1/4= 2(x – 3)+1/4`

   `=>3/4x-1/4=2x-6+1/4`

   `=>3/4x-1/4-1/4=2x-6`

   `=>3/4x-(1/4+1/4)=2x-6`

   `=>3/4x-1/2=2x-6`

   `=>3/4x-1/2+6=2x`

   `=>3/4x+11/2=2x`

   `=>11/2=2x-3/4x`

   `=>11/2=(2-3/4)x`

   `=>11/2=5/4x`

   `=>x=22/5`

   $\\$

   `30%x-x+5/6=49/2`

   `=>3/10x-x+5/6=49/2`

   `=>(3/10-1)x+5/6=49/2`

   `=>(-7)/10x=49/2-5/6`

   `=>(-7)/10x=71/3`

   `=>x=(-710)/21`

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2. Đáp án:

   `a,`

   `3/4x – 1/4 = 2 (x -3) + 1/4`

   `⇔ 3/4x – 1/4 = 2x – 6 + 1/4`

   `⇔ 3/4x – 1/4 = 2x – 23/4`

   `⇔ 3/4x – 1/4 – 2x + 23/4 = 0`

   `⇔ (3/4x – 2x) + (-1/4 + 23/4) = 0`

   `⇔ -5/4x + 11/2 = 0`

   `⇔ -5/4 = 0 – 11/2`

   `⇔ -5/4 = -11/2`

   `⇔ x = -11/2 : (-5/4)`

   `⇔ x = 22/5`

   `text{Vậy}` `x = 22/5`

   `b,`

   `30%x – x + 5/6 = 49/2`

   `⇔ (30% – 1)x = 49/2 – 5/6`

   `⇔ -7/10x = 71/3`

   `⇔ x = 71/3 : (-7/10)`

   `⇔ x = -710/21`

   `text{Vậy}` `x=  (-710)/21`

    

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