$x.(2 + x).( 7 – x) = 0$
⇔\(\left[ \begin{array}{l}x=0\\2+x=0\\7-x=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-2\\x=7\end{array} \right.\)
$(x - 1).(x +2).(-x -3) = 0$
⇔\(\left[ \begin{array}{l}x-1=0\\x+2=0\\-x-3=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=1\\x=-2\\x=-3\end{array} \right.\)