a ) $| 2x | = x - 6$
⇒\(\left[ \begin{array}{l}2x=x-6 ⇔ x = - 6\\2x=6-x ⇔ x = 2\end{array} \right.\)
b ) $| - 3x | = x - 8$
⇒\(\left[ \begin{array}{l}-3x=x-8 ⇔ x = 2\\-3x=8-x ⇔ x = -4\end{array} \right.\)
c ) $| 4x | = 2x + 2$
⇒\(\left[ \begin{array}{l}4x=2x+2 ⇔ x = 1\\4x=-2x-2⇔ x = -$\dfrac{1}{3}$ \end{array} \right.\)
d ) $| -5x | - 16 = 3x$
$5x - 16 = 3x$
$2x = 16$
$x = 8$
Bài 2 :
$a ) | | x - 1 | + 2 | = 7$
⇒\(\left[ \begin{array}{l}| x - 1 | + 2 = 7⇔ | x - 1 | = 5 \\| x- 1 | + 2 = -7⇔ | x -1 | =-9\end{array} \right.\)
$+) | x- 1 | = 5$
⇒\(\left[ \begin{array}{l}x-1 = 5 ⇒ x = 6\\x-1=-5⇒x=-4\end{array} \right.\)
$+) | x -1 | =-9$ $( $ loại vì $| x - 1 | ≥ 0 ∀ x )$
$b) | 2 - x | -|2x - 3 | = 0$
$ |2-x| = | 2x-3|$
⇒\(\left[ \begin{array}{l}2-x=2x-3⇒x=\\2-x=3-2x⇒x=1\end{array} \right.\) $\dfrac{5}{3}$
