1. 对利润函数 \( f = p_1q_1 + p_2q_2 - c \) 进行微分,得到:
\[ f_p = -0.2p_1^2 - 0.05p_2^2 + 32p_1 + 12p_2 - 1395 \]
2. 对 \( p_1 \) 进行偏微分,并设其偏导数为零:
\[ \frac{\partial f}{\partial p_1} = -0.4p_1 + 32 = 0 \]
解得 \( p_1 = \frac{32}{0.4} = 80 \)
3. 对 \( p_2 \) 进行偏微分,并设其偏导数为零:
\[ \frac{\partial f}{\partial p_2} = -0.1p_2 + 12 = 0 \]
解得 \( p_2 = \frac{120}{0.1} = 1200 \)
4. 将 \( p_1 = 80 \) 和 \( p_2 = 120 \) 代入原利润函数:
\[ f = -(80 - p_1)^2/5 - (120 - p_2)^2/20 + 605 \]
由于 \( (80 - p_1)^2 \) 和 \( (120 - p_2)^2 \) 都是平方项,它们不会为负。
5. 为了求最大利润,我们令 \( p_1 = 80 \) 和 \( p_2 = 120 \):
\[ \text{最大利润} = 605 \]
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