一道数学题　　转不过弯来

numberunique · 发表于 2006-5-30 09:24:00

If * represents one of the operations + ,- ,and X ,

is k*(l+m)=(k*l)+(k*m) for all numbers k,l,and m?

A k*1 is not equal to 1*k for some numbers k

B * represents subtraction

答案是Ｄ为什么呀　　我怎么觉得都不充分

k-(l+m)=k-l+k-m ??????????????

[此贴子已经被作者于2006-5-30 10:59:09编辑过]

feier_79 · 发表于 2006-5-30 09:30:00

A可以推出*代表减号

yaoyao99 · 发表于 2006-5-30 09:30:00

It's (k-l) x (k-m) not (k-l) + (k-m)

numberunique · 发表于 2006-5-30 11:01:00

A =>代表-号 since k-(l+m)不=(k-l)+(k-m) 那不是不充分吗?

yaoyao99 · 发表于 2006-5-30 11:28:00

Sorry, I could have swore that the question said k*(l+m)=(k*l)(k*m) earlier..

Anyway, you can get the answer "no, it's not going to be equal for all numbers" from either condition. The answer doesn't have to be yes.

caesar2005 · 发表于 2006-5-30 12:24:00

此处涉及到充分否定是否也算是充分的问题。

1战的时候，跟几个人讨论过，如果可以充分否定，也算是充分的。

numberunique · 发表于 2006-5-31 10:52:00

谢谢楼上两位大侠解决了我一个疑惑

一道数学题　　转不过弯来