效用限制線問題 - 經濟

問題 :
The utility of A(aconsumer/borrower)is U(C1,C2)=C1C2, where C1 is the

consumption today and C2 is the consumpyion tomorrow. A has $Y1 today

and $Y2 tomorrow, Y1<Y2. To simplify, assume that interest rate is r＝0

and therefore the budget constraint is C1+C2=Y1+Y2. The consumer has a

credit limit of $q so that C1-Y1<=q. The utility maximization problem is

: max C1C2

subject to : C1+C2=Y1+Y2, C1-Y1<=q

(a) State the Lagrangian of the problem and the K-T conditions

(b) Find the solution (there 2 cases)

第一小題没什麼問題，但不懂第二小題為什麼有兩個cases

希望大家解答，謝謝:)

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