Bài 2 :tìm x a,-1/2 x +3/4=5/7 b,|x=1/2|-5/9=6/11

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1. $a, -1/2x+3/4=5/7$

   $=>-1/2x=-1/28$

   $=>x=1/14$

   $b, |x-1/2|-5/9=6/11$

   $=>|x-1/2|=109/99$

   $Th1: x-1/2=109/99$

   $=>x=317/198$

   $Th2:x-1/2=-109/99$

   $=>x=-119/198$

   $Vậy: x=317/198,x=-119/198$

   (Học tốt nhé!)

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2. Giải thích các bước giải:

   `a)`
   `-1/2 x+3/4=5/7`
   `=>-1/2x=5/7-3/4`
   `=>-1/2x=20/28-21/28`
   `=>-1/2x=-1/28`
   `=>x=-1/28:(-1)/2`
   `=>x=-1/28 . (-2)`
   `=>x=1/14`
   Vậy `x=1/14`
   `b)`
   `|x+1/2|-5/9=6/11`
   `=>|x+1/2|=6/11+5/9`
   `=>|x+1/2|=54/99+55/99`
   `=>|x+1/2|=109/99`
   `=>`\(\left[ \begin{array}{l}x+\dfrac{1}{2}=\dfrac{109}{99}\\x+\dfrac{1}{2}=\dfrac{-109}{99}\end{array} \right.\) 
   `=>`\(\left[ \begin{array}{l}x=\dfrac{109}{99}-\dfrac{1}{2}\\x=\dfrac{-109}{99}-\dfrac{1}{2}\end{array} \right.\) 
   `=>`\(\left[ \begin{array}{l}x=\dfrac{119}{198}\\x=\dfrac{-317}{198}\end{array} \right.\) 
   Vậy `x\in{119/198;-317/198}`

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