Gaokao Math Practice Question
设 $x, y$ 满足约束条件 $\left\{\begin{array}{l}x+y-7 \leqslant 0 \\ x-3 y+1 \leqslant 0 \\ 3 x-y-5 \geqslant 0,\end{array}\right.$ 则 $z=2 x-y$ 的最大值为 ($\qquad$)
- A.10
- B.8
- C.3
- D.2
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