1.Tìm x biết: 2 và 1/2 -x+4/5=2/3-(-4/7) 1 và 4/5=-0,15-x -4/7-x=3/5-2x (3/8-1/5)+(5/8-x)=1/5 2.Q=9-|x-1/10|

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1. `a)` `2(1)/(2)-x+4/5=2/3-(-4/7)`

   `⇔5/2-x+4/5=2/3+4/7`

   `⇔5/2+4/5-x=14/21+12/21`

   `⇔25/10+8/10-x=26/21`

   `⇔33/10-x=26/21`

   `⇔x=33/10-26/21`

   `⇔x=693/210-260/210`

   `⇔x=433/210`

   `b)` `1(4)/(5)=-0,15-x`

   `⇔9/5=-3/20-x`

   `⇔9/5+(-3/20)=x`

   `⇔x=-3/20-9/5`

   `⇔x=-39/20`

   `c)` `-4/7-x=3/5-2x`

   `⇔-x+2x=3/5+4/7`

   `⇔x=41/35`

   `d)` `(3/8-1/5)+(5/8-x)=1/5`

   `⇔3/8-1/5+5/8-x=1/5`

   `⇔3/8+5/8-1/5-x=1/5`

   `⇔1-1/5-x=1/5`

   `⇔4/5-x=1/5`

   `⇔x=4/5-1/5=3/5`

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2. `a)` `2(1)/(2)-x+4/5=2/3-(-4/7)`

   `⇒5/2-x+4/5=2/3+4/7`

   `⇒5/2+4/5-x=14/21+12/21`

   `⇒25/10+8/10-x=26/21`

   `⇒33/10-x=26/21`

   `⇒x=33/10-26/21`

   `⇒x=693/210-260/210`

   `⇒x=433/210`

   `b)` `1(4)/(5)=-0,15-x`

   `⇒9/5=-3/20-x`

   `⇒9/5+(-3/20)=x`

   `⇒x=-3/20-9/5`

   `⇒x=-39/20`

   `c)` `-4/7-x=3/5-2x`

   `⇒-x+2x=3/5+4/7`

   `⇒x=41/35`

   `d)` `(3/8-1/5)+(5/8-x)=1/5`

   `⇒3/8-1/5+5/8-x=1/5`

   `⇒3/8+5/8-1/5-x=1/5`

   `⇒1-1/5-x=1/5`

   `⇒4/5-x=1/5`

   `⇒x=4/5-1/5=3/5`

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