1.
$|a|=4$
→ \(\left[ \begin{array}{l}a=4\\a=-4\end{array} \right.\)
2.
$3×|a|+6=12$
$3×|a|=12-6$
$3×|a|=6$
$|a|=6:3$
$|a|=3$
→ \(\left[ \begin{array}{l}a=3\\a=-3\end{array} \right.\)
3.
$|a+3|=-3$
$→ a∈Ф$
4.
$|a-2|+3=14$
$|a-2|=14-3$
$|a-2|=11$
→ \(\left[ \begin{array}{l}a-2=11\\a-2=-11\end{array} \right.\) ⇒ \(\left[ \begin{array}{l}a=11-2\\a=(-11)-2\end{array} \right.\) ⇒\(\left[ \begin{array}{l}a=9\\a=-13\end{array} \right.\)