500 DS tricky

dunkin77 · Posted: Mon Apr 02, 2007 3:30 pm Post subject: 500 DS tricky

Hi,

I thought the answer is E) but the correct answer is B).

i) says if there is 2, there should be -2 in S; however, ii) says a and b (differrent number) can be multiplied "ab" but it dose not say same number a and -a can be multiplied..... I am confused.. Crying or Very sad

. S is a set of integers such that
i) if a is in S, then –a is in S, and
ii) if each of a and b is in S, then ab is in S.
Is –4 in S?
(1) 1 is in S.
(2) 2 is in S.

ajith · Posted: Mon Apr 02, 2007 6:39 pm Post subject: Re: 500 DS tricky

dunkin77 · Posted: Mon Apr 02, 2007 8:33 pm Post subject:

Okie - a and -a is different number then! Wink