Giải thích các bước giải:
$a)\dfrac{2}{3}x+\dfrac{5}{7}=\dfrac{3}{10}$
$\dfrac{2}{3}x=\dfrac{-29}{70}$
$x=\dfrac{-87}{140}$
$b)-21x+\dfrac{1}{3}=-\dfrac{2}{3}$
$-21x=-1$
$x=\dfrac{1}{21}$
$c)|x-1,5|=2$
$<=>$\(\left[ \begin{array}{l}x-1,5=2\\x-1,5=-2\end{array} \right.\) $<=>$\(\left[ \begin{array}{l}x=3,5\\x=-0,5\end{array} \right.\)
$d)|x+\dfrac{3}{4}|-\dfrac{1}{2}=0$
$|x+\dfrac{3}{4}|=\dfrac{1}{2}$
$<=>$\(\left[ \begin{array}{l}x+\dfrac{3}{4}=\dfrac{1}{2}\\x+\dfrac{3}{4}=-\dfrac{1}{2}\end{array} \right.\) $<=>$\(\left[ \begin{array}{l}x=-\dfrac14\\x=-\dfrac54\end{array} \right.\)
