Tìm x ( x + 6/7) . ( |x| – 1/2) = 0 20% x – x + 1/5 = 3/4

`(x + 6/7) . (|x| – 1/2) = 0`

`=>` \(\left[ \begin{array}{l}x + \dfrac{6}{7} = 0\\|x| – \dfrac{1}{2} = 0\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x = \dfrac{-6}{7}\\|x| = \dfrac{1}{2}\end{array} \right.\) 

`=> x ∈ {(-6)/7 ; 1/2 ; (-1)/2}`

`20% x – x + 1/5 = 3/4`

`=> 1/5 . x – x + 1/5 = 3/4`

`=> x . (1/5 – 1) = 3/4 – 1/5`

`=> x . (-4)/5 = 11/20`

`=> x = 11/20 : (-4)/5`

`=> x = 11/20 . (-5)/4`

`=> x = (-11)/16`