\(3,\\ a,=-3,8+3,8-5,7=-5,7\\ b,=31,4+6,4-18=37,8-18=19,8\\ c,=\left(-9,6+9,6\right)+\left(4,5-1,5\right)=3\\ d,=3,1-2,5+2,5-3,1=\left(3,1-3,1\right)-\left(2,5-2,5\right)=0\\ e,=5,3-2,8-5-5,3=\left(5,3-5,3\right)-\left(2,8+5\right)=-7,8\)
\(4,\\ \left(x+3\right)\left(x-2\right)< 0\\ \Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x+3< 0\\x-2>0\end{matrix}\right.\\\left\{{}\begin{matrix}x+3>0\\x-2< 0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< -3\\x>2\end{matrix}\right.\\\left\{{}\begin{matrix}x>-3\\x< 2\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x\in\varnothing\\-3< x< 2\end{matrix}\right.\\ \Leftrightarrow-3< x< 2\)
