Đáp án: a) (-1).(-3).(-6).x=36
⇔ -18x =36
⇔ x = 36:(-18)
⇔ x = -2
b) l 1-4x l =7
⇒ 1-4x = ±7
⇒ \(\left[ \begin{array}{l}1-4x=7\\1-4x= -7\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}4x= -6\\4x=8\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x=-3/2\\x=2\end{array} \right.\)