For each system, determine if it is in standard form.

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Maximize $$P = 6 x_1 + 4 x_2 + 6 x_3$$ subject to the constraints

$$\begin{array}{rrrrrcr} x_1 & - & x_2& + & x_3 & \le & 9 \cr && &&x_{1} & \le & 9 \end{array}$$
$$x_1\ge 0 \qquad x_2 \ge 0 \qquad x_{3} \ge 0$$

A. Yes, in standard form.
B. No, not in standard form.

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Maximize $$P = x_1 + 9 x_2 + x_3$$ subject to the constraints

$$\begin{array}{rrrrrcr} 5 x_1 & + & x_2& + & x_3 & \le & - 8 \cr 8 x_1 & + & 7 x_2& - & x_3 & \le & 7 \end{array}$$
$$x_1\ge 0 \qquad x_2 \ge 0 \qquad x_{3} \ge 0$$

A. Yes, in standard form.
B. No, not in standard form.

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Maximize $$P = 5 x_1 + x_2$$ subject to the constraints

$$\begin{array}{rrrcr} 8 x_1 & + & x_2 & \le & 9 \cr 7 x_1 & - & x_2 &\ge & 3 \cr x_1\ge 0 && x_2 & \ge & 0 \end{array}$$

A. Yes, in standard form.
B. No, not in standard form.

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Maximize $$P = 6 x_1 + 3 x_2 + x_3$$ subject to the constraints

$$\begin{array}{rrrrrcr} x_1 & + & 8 x_2& + & 5 x_3 & \le & 7 \cr && &&x_{1} & \ge & 0 \end{array}$$

A. Yes, in standard form.
B. No, not in standard form.

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Maximize $$P = 3 x_1 + 7 x_2$$ subject to the constraints

$$\begin{array}{rrrcr} 3 x_1 & + & x_2 & \le & 9 \cr x_1 &+ &10x_2 &\le &77 \cr x_1\ge 0 &&x_2 & \ge & 0 \end{array}$$

A. Yes, in standard form.
B. No, not in standard form.