Question

Tìm x:

|| 1/2x + 1 | - 3/4| = 2/5

Answer 1

`||1/2x+1|-3/4|=2/5`

`@TH1:|1/2x+1|-3/4=2/5`

      `=>|1/2x+1|=23/20`

      `=>` $\left[\begin{matrix}\dfrac{1}{2}x+1=\dfrac{23}{20}\\ \dfrac{1}{2}x+1=\dfrac{-23}{20}\end{matrix}\right.$

      `=>` $\left[\begin{matrix} x=\dfrac{3}{10}\\ x=\dfrac{-43}{10}\end{matrix}\right.$

`@TH2:|1/2x+1|-3/4=-2/5`

       `=>|1/2x+1|=7/20`

       `=>` $\left[\begin{matrix}\dfrac{1}{2}x+1=\dfrac{7}{20}\\ \dfrac{1}{2}x+1=\dfrac{-7}{20}\end{matrix}\right.$

       `=>` $\left[\begin{matrix} x=\dfrac{-13}{10}\\ x=\dfrac{-27}{10}\end{matrix}\right.$

Vậy `x in {3/10;-43/10;-13/10;-27/10}`

Answer 2