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If x^3 * y^6 * z^9 < 0, which of the following must be tr

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by gmatv09 » Sun Sep 06, 2009 2:35 pm
IMO C
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by kbharadwaj.1987 » Sun Sep 06, 2009 3:00 pm
I didn't get it, could anyone explain it?
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by PussInBoots » Sun Sep 06, 2009 4:02 pm
x^3 * y^6 * z^9 < 0
(x * y^2 * z^3)^3 < 0
x * y^2 * z^3 < 0
x * z^3 < 0 (y^2 is non-negative)
x * z * z^2 < 0
xz <0

y could be whatever. As long as it's not zero, y^6 will be positive
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by kbharadwaj.1987 » Sun Sep 06, 2009 4:19 pm
oh thanks mate!
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by hansoo » Mon Sep 07, 2009 1:53 am
The official answer is C.

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