Lời giải:
$42.(28-9)-28.(42+9)$
$=42.19-28.51$
$=798-1428$
$=-630$
$|x+2|-9=(-5).(-6)$
$<=>|x+2|=39$
<=>\(\left[ \begin{array}{l}x+2=39\\x+2=-39\end{array} \right.\)
<=>\(\left[ \begin{array}{l}x=37\\x=-41\end{array} \right.\)
Vậy \(\left[ \begin{array}{l}x=37\\x=-41\end{array} \right.\)