2 tìm x biết A) (2x-1/2 ) *2+(1/2+1/3+1/4):1/8=1 B) (x-3)(4-5x)=0

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1. `a, (2x-1/2) .2+(1/2+1/3+1/4):1/8=1`

   `⇒ (2x-1/2) .2+13/12:1/8=1`

   `⇒ (2x-1/2) .2+26/3=1`

   `⇒ (2x-1/2) .2 = -23/3`

   `⇒ 2x – 1/2 = -23/6`

   `⇒ 2x = -10/3`

   `⇒ x = -5/3`

   `b, (x – 3)(4 – 5x) = 0`

   `⇒` \(\left[ \begin{array}{l}x – 3=0\\4 – 5x=0\end{array} \right.\) 

   `⇒` \(\left[ \begin{array}{l}x = 3\\ 5x=4\end{array} \right.\) 

   `⇒ x = 5` và `x = 4/5`

    

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2. Giải thích các bước giải:

   `A) (2x-1/2 ) *2+(1/2+1/3+1/4):1/8=1`
   `=>(2x-1/2).2+13/12:1/8=1`
   `=>(2x-1/2).2+13/12. 8 =1`
   `=>(2x-1/2).2+26/3=1`
   `=>(2x-1/2).2=-23/3`
   `=>2x-1/2=-23/3:2`
   `=>2x-1/2=-23/3 . 1/2`
   `=>2x-1/2=-23/6`
   `=>2x=-23/6+1/2`
   `=>2x=-23/6+3/6`
   `=>2x=-20/6`
   `=>x=-5/3`
   `B) (x-3)(4-5x)=0`
   TH`1`
   `x-3=0=>x=0+3=>x=3`
   TH`2`
   `4-5x=0=>5x=4-0=>5x=4=>x=4/5`

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