Đáp án:mk chỉ làm đến câu 17 thôi

Giải thích các bước giải:

$12,|x+3|=1\dfrac{1}{4}$

$=>|x+3|=\dfrac{5}{4}$

$=>\left[ \begin{array}{l}x+3=\dfrac{5}{4}\\x+3=-\dfrac{5}{4}\end{array} \right.$

$=>\left[ \begin{array}{l}x=\dfrac{-7}{4}\\x=-\dfrac{17}{4}\end{array} \right.$

$13,|x-7|=-\dfrac{-5}{3}$

$=>|x-7|=\dfrac{5}{3}$

$=>\left[ \begin{array}{l}x-7=\dfrac{5}{3}\\x-7=-\dfrac{5}{3}\end{array} \right.$

$=>\left[ \begin{array}{l}x=\dfrac{26}{3}\\x=\dfrac{16}{3}\end{array} \right.$

$14,|x+9|=-\dfrac{4}{-3}$

$=>|x+9|=\dfrac{4}{3}$

$=>\left[ \begin{array}{l}x+9=\dfrac{4}{3}\\x+9=-\dfrac{4}{3}\end{array} \right.$

$=>\left[ \begin{array}{l}x=-\dfrac{23}{3}\\x=-\dfrac{31}{3}\end{array} \right.$

$15,|x-1|=3\dfrac{1}{2}$

$=>|x-1|=\dfrac{7}{2}$

$=>\left[ \begin{array}{l}x-1=\dfrac{7}{2}\\x-1=-\dfrac{7}{2}\end{array} \right.$

$=>\left[ \begin{array}{l}x=\dfrac{9}{2}\\x=-\dfrac{5}{2}\end{array} \right.$

`16,|x+5|=|\frac{-2}{3}|`

`=>|x+5|=\frac{2}{3}`

$=>\left[ \begin{array}{l}x+5=\dfrac{2}{3}\\x+5=-\dfrac{2}{3}\end{array} \right.$

$=>\left[ \begin{array}{l}x=-\dfrac{13}{3}\\x=-\dfrac{17}{3}\end{array} \right.$

`17,|x-4|=-(\frac{-3}{5})`

`=>|x-4|=\frac{3}{5}`

$=>\left[ \begin{array}{l}x-4=\dfrac{3}{5}\\x-4=-\dfrac{3}{5}\end{array} \right.$

$=>\left[ \begin{array}{l}x=\dfrac{23}{5}\\x=\dfrac{17}{5}\end{array} \right.$