作者redpop (poopoo)
看板Economics
标题[请益] Price Theory by Landsburg 的租税归宿
时间Tue May 1 16:47:00 2012
小弟虽然已修完个、总体外加财政学,但一直没有数学的底子（汗）
最近重翻Landsburg的Price theory想把书末的Calculus Supplement题目做完
从最基础打起,结果在Chapter1 马上就卡题！希望版上善良、聪明的板友们可以指点一下
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Let S(P) and D(P) be the supply and demand functions for apples. Suppose that
an excise tax of T is imposed and the posttax equilibrium price for apples is
P. Treating P as a function of T, (1) use the equation:
D(P) = S(P-T) --------"1"
and the chain rule to derive a formula for the derivative dP/dT.
(2) Let Ps be the price that sllers actually receive. Use the result of
problem 1 and the equation :
Ps = P - T --------"2"
to derive and simplify a formula for the derivative dPs/dT.
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在此提供第一题解答：
dP/dT = S'(P-T) / ( S'(P-T) - D'(P) )
其实我直接把"2"代换入"1"做全微分出来的答案好像也没有错,但这样真的妥当吗？
哪位好心的版友可以告诉我如何使用dP/dT求出正解？如果可以顺便附上算式过程
感恩！
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