Đáp án:
Giải thích các bước giải:
$a,-\dfrac{2}{15}-x=\dfrac{-3}{10}$
$⇔x=\dfrac{-2}{15}-\left (\dfrac{-3}{10} \right )$
$⇔x=\dfrac{1}{6}$
$b,\left |x+\dfrac{1}{2} \right |-\dfrac{1}{2}=\sqrt{9}$
$⇔\left |x+\dfrac{1}{2} \right |=3+\dfrac{1}{2}$
$⇔\left |x+\dfrac{1}{2} \right |=\dfrac{7}{2}$
$⇔\left[ \begin{array}{1}x+\dfrac{1}{2}=\dfrac{7}{2}\\x+\dfrac{1}{2}=\dfrac{-7}{2}\end{array} \right.$
$⇔\left[ \begin{array}{1}x=3\\x=-4\end{array} \right.$
