bài 1a)x-2/5=1-x/6 b)22/5+1/2.x^2=4.8/5 c)7/2-|x-1/3|=5/2

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1. Đáp án-Giải thích các bước giải:

   Bài 1:

   a)`x-2/5=1-x/6`

   `<=>x+x/6=1+2/5`

   `<=>7/6x=7/5`

   `<=>x=7/5:7/6`

   `<=>x=7/5 . 6/7`

   `<=>x=6/5`

   Vậy `x=6/5`

   b)`22/5+1/2.x^2=4.8/5`

   `<=>22/5 + 1/2.x^2=32/5`

   `<=>1/2 . x^2=32/5-22/5`

   `<=>1/2 .x^2=2`

   `<=>x^2=2:1/2`

   `<=>x^2=4`

   `<=>x=+-2`

   Vậy `x=+-2`

   c)`7/2-|x-1/3|=5/2`

   `<=>|x-1/3|=7/2-5/2`

   `<=>|x-1/3|=1`

   +) `x-1/3=1`

   `<=>x=1+1/3`

   `<=>x=4/3`

   +)`x-1/3=-1`

   `<=>x=-1+1/3`

   `<=>x=-2/3`

   Vậy `x=4/3;x=-2/3.`

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2. a) `x-2/5 =1-x/6`

   `x+x/6=1+2/5`

   `x.(1+1/6)=7/5`

   `x . 7/6 =7/5`

   `x=7/5 : 7/6`

   `x=6/5`

   b) `22/5 +1/2 .x^2=4. 8/5`

   `22/5 + 1/2 .x^2=32/5`

   `1/2 .x^2=32/5-22/5`

   `1/2 .x^2= 2`

   `x^2 = 2: 1/2`

   `x^2=4`

   `x=2^2=(-2)^2`

   c) `7/2 -|x-1/3|=5/2`

   `|x-1/3|=7/2-5/2`

   `|x-1/3|=1`

   \(\left[ \begin{array}{l}x-\dfrac{1}{3}=1\\x-\dfrac{1}{3}=-1\end{array} \right.\) 

   \(\left[ \begin{array}{l}x=1+\dfrac{1}{3}\\x=-1+\dfrac{1}{3}\end{array} \right.\) 

   \(\left[ \begin{array}{l}x=\dfrac{4}{3}\\x=\dfrac{-2}{3}\end{array} \right.\) 

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