122. An operation Q is defined by the equation aQb=(a-b)/(a+b), for all numbers a and b such that a 不等於 b. If a 不等於 -c, and aQc=0, then c=?
(A)-a
(B)-1/a
(C)0
(D)1/a
(E)a
Ans: (E)
解題的時候用不到aQb=(a-b)/(a+b)條件,只知道a+c不等於0和a-b不等於0,不知道自己思考有沒有錯...
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