4.
已知实数\(x\),\(y\)满足\(\begin{cases}x-3y-6\leqslant 0, \\ y\leqslant 2x+4, \\ 2x+3y-12\leqslant 0,\end{cases}\)直线\((1+\)\(λ\)\()\)\(x\)\(+(1-2\)\(λ\)\()\)\(y\)\(+3\)\(λ\)\(-12=0 (\)\(λ\)\(∈R)\)过定点\(A\)\((\)\(x\)\({\,\!}_{0}\),\(y\)\({\,\!}_{0})\),则\(z\)\(= \dfrac{y-y_{0}}{x-x_{0}}\)的取值范围为( )