a. 2|3-x|-3 = 0
$<=> 2|3-x| = 0+3$
$<=>2|3-x|= 3$
$<=> |3-x| = 3:2$
$<=> |3-x| = 1,5$
$<=>$ \(\left[ \begin{array}{l}3-x = 1,5\\3-x = -1,5\end{array} \right.\)
$<=>$ \(\left[ \begin{array}{l}x = 1,5\\x = 4,5\end{array} \right.\)
$Vậy ...$
b. $3x$ - $\frac{5}{4}$ $= 0,3 - 9,11$
$<=>$ $3x$ - $\frac{5}{4}$ $= -8,81$
$<=>$ $3x$ = $-8,81$ + $\frac{5}{4}$
$<=> 3x = -7,56$
$<=>x = -7,56 : 3$
$<=> x = -2,52$
$Vậy x = -2,52$
