以下是引用yangao在2006-1-3 2:51:00的发言:11th OG DS 89 If 。represents one of the operations +,-,and *, is k。(L+m)=(k。L)+(k。m) for all numbers k,L,and m? (1)k。1 is not equal to 1。k for some number k. (2) 。represents subtraction. The correct answer is D (1)For operations + and -(*?), k。1 is equal to 1。k since both k+1=1+k and also k-1=1-k. (*?) Therefore, the operation represented must be subtration. From this , It is possible to determine whether k-(L+m)=(k-L)+(k-m) holds for all numbers k,L,and m; sufficient. (2)The information is given directly that the operation represented is subtration. Once again, it can be determined whether k-(L+m)=(k-L)+(k-m) holds for all numbers k,L, and m; sufficent. 我的问题是为什么k-1=1-k. 请教各位
我没有11TH OG,所以不知道原题目怎么样的,我觉得,这里是弄错了吧?应该是k*1=1*k 乘号?那样就说得通了
由(1)可知符号“。”代表减号。From this , It is possible to determine whether k-(L+m)=(k-L)+(k-m) holds for all numbers k,L,and m; sufficient. 同理,(2)sufficent. |