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

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}`