要求出上述需求函数的雅可比矩阵,我们首先需要理解雅可比矩阵的概念。在数学中,对于一个由多个变量构成的向量值函数,其雅可比矩阵是该函数所有一阶偏导数所组成的矩阵。
考虑给定的需求函数 \(x(p,w) = \left( x_1(p,w), x_2(p,w), x_3(p,w) \right)\),其中
\[x_1(p,w)=\frac{p^2}{p_3}\]
\[x_2(p,w)=-\frac{p_1}{p_3}\]
\[x_3(p,w)=\frac{w}{p_3}\]
这里,\(p\) 是价格向量 \((p_1, p_2, p_3)\),而 \(w\) 是消费者的财富。
雅可比矩阵 J 的一般形式为
\[J = \left( \begin{array}{ccc}
\frac{\partial x_1}{\partial p_1} & \frac{\partial x_1}{\partial p_2} & \frac{\partial x_1}{\partial p_3} & \frac{\partial x_1}{\partial w} \\
\frac{\partial x_2}{\partial p_1} & \frac{\partial x_2}{\partial p_2} & \frac{\partial x_2}{\partial p_3} & \frac{\partial x_2}{\partial w} \\
\frac{\partial x_3}{\partial p_1} & \frac{\partial x_3}{\partial p_2} & \frac{\partial x_3}{\partial p_3} & \frac{\partial x_3}{\partial w}
\end{array} \right)\]
具体计算如下:
- 对于 \(x_1(p,w)=\frac{p^2}{p_3}\),
\[\frac{\partial x_1}{\partial p_1} = 0,\]
\[\frac{\partial x_1}{\partial p_2} = \frac{2p_2}{p_3},\]
\[\frac{\partial x_1}{\partial p_3} = -\frac{p^2}{p_3^2},\]
\[\frac{\partial x_1}{\partial w} = 0.\]
- 对于 \(x_2(p,w)=-\frac{p_1}{p_3}\),
\[\frac{\partial x_2}{\partial p_1} = -\frac{1}{p_3},\]
\[\frac{\partial x_2}{\partial p_2} = 0,\]
\[\frac{\partial x_2}{\partial p_3} = \frac{p_1}{p_3^2},\]
\[\frac{\partial x_2}{\partial w} = 0.\]
- 对于 \(x_3(p,w)=\frac{w}{p_3}\),
\[\frac{\partial x_3}{\partial p_1} = 0,\]
\[\frac{\partial x_3}{\partial p_2} = 0,\]
\[\frac{\partial x_3}{\partial p_3} = -\frac{w}{p_3^2},\]
\[\frac{\partial x_3}{\partial w} = \frac{1}{p_3}.\]
因此,需求函数的雅可比矩阵为
\[J = \left( \begin{array}{cccc}
0 & \frac{2p_2}{p_3} & -\frac{p^2}{p_3^2} & 0 \\
-\frac{1}{p_3} & 0 & \frac{p_1}{p_3^2} & 0 \\
0 & 0 & -\frac{w}{p_3^2} & \frac{1}{p_3}
\end{array} \right)\]
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