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section 19 #19

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dunkin77 Master | Next Rank: 500 Posts Default Avatar
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section 19 #19

Post Tue May 01, 2007 6:55 am
. Is ab = 1 ?
(1) aba = a
(2) bab = b


Hi
I thought the answer was D) but turned ouy to be E).... can you please help?

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jayhawk2001 Community Manager
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Post Tue May 01, 2007 8:57 pm
dunkin77 wrote:
. Is ab = 1 ?
(1) aba = a
(2) bab = b


Hi
I thought the answer was D) but turned ouy to be E).... can you please help?
You cannot cancel out a in (1) without knowing that a != 0. Think of it
this way x * 0 = 0. Can you cancel out 0 from both sides and say x = 1?
No.

Same with b in (2).

Since we don't know that a!=0 and b!=0, the answer is E

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