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Sec 19 Q17 DS1000

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Sec 19 Q17 DS1000

by gviren » Tue Jun 05, 2007 5:05 pm
The OA is E, I think it should be C


1) aba=a so a^2b-a=0
a(ab-1) = 0

so either a=0 or ab=1

2)

aba=b so b^2a-b=0
b(ab-1) = 0

so either b=0 or ab=1

combining 1 and 2, ab=1


Please help
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by jayhawk2001 » Tue Jun 05, 2007 9:54 pm
Combining (1) and (2), we still have 2 options -- ab = 1, or (a=0, b=0)

Please note that (1) and (2) are both satisfied for a = 0, b = 0

Hence E
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