关于 效用函数的一个问题 即证明U=U（X1,X2）（已知效用函数连续可导）即证明U=U（X1,X2）（已知效用函数连续可导）试证明：U11 *（U2 ）^2－ 2* U1* U2* U12 ＋ （U1 ）^2 * U22（效用最大化的二阶

关于 效用函数的一个问题 即证明U=U（X1,X2）（已知效用函数连续可导）即证明U=U（X1,X2）（已知效用函数连续可导）试证明：U11 *（U2 ）^2－ 2* U1* U2* U12 ＋ （U1 ）^2 * U22（效用最大化的二阶
关于 效用函数的一个问题 即证明U=U（X1,X2）（已知效用函数连续可导）
即证明U=U（X1,X2）（已知效用函数连续可导）试证明：
U11 *（U2 ）^2－ 2* U1* U2* U12 ＋ （U1 ）^2 * U22（效用最大化的二阶条件）
如何证明啊 高版的书上面有过程 关键是求二阶的那儿 U1/u2 对X1求导怎么就 变成了那样的形式（不敲出来了）
难道U11 不是 U对 X1连续求两次偏导数的意思吗?
（同理 U12 即 U 先对X1 求偏导 然后再对X2求偏导 我这样理解不正确吗）
我是跨考的 没学过经济学...
如果特殊符号打不出来的 可以用word 发给我
..
事成再补100分

关于 效用函数的一个问题 即证明U=U（X1,X2）（已知效用函数连续可导）即证明U=U（X1,X2）（已知效用函数连续可导）试证明：U11 *（U2 ）^2－ 2* U1* U2* U12 ＋ （U1 ）^2 * U22（效用最大化的二阶
效用最大化的二阶条件,应该是在无条件极值里面的.
这样考虑,在一元的时候,极大值就是一阶导为0,二阶导为负.
那么二元的时候也类似,极大值就是一阶微分为0,二阶微分为负定.
设U11=A,U12=B,U22=C.
U11(dx)^2+2U12dxdy+U22(dy)^2负定,即是A<0,B^2-AC<0.这就是二阶条件,绿皮书那本习题指导上似乎也提到过.
你说的那个效用最大化的二阶条件在哪儿看到的,高鸿业的书我也有,78页下面对二阶条件是略去的

It can be simple to neglect something as straightforward as you are trying to remodel or design Hinges. On the other hand, picking out the right hardware is very significant in that the incorrect ones...

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