$|x+7|=|x+10|$
$⇔ \left[ \begin{array}{l}x+7=x+10\\x+7=-(x+10)\end{array} \right.$
$⇔ \left[ \begin{array}{l}0x=3\\2x=-17\end{array} \right.$
$⇒ x=-\dfrac{17}{2}$
$|3x|-|x-1|=0$
$⇔ |3x|=|x-1|$
$⇔ \left[ \begin{array}{l}3x=x-1\\3x=-(x-1)\end{array} \right.$
$⇔ \left[ \begin{array}{l}2x=-1\\4x=1\end{array} \right.$
$⇔ \left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=\dfrac{1}{4}\end{array} \right.$
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CORRECT- Đúng không cần check!
