Can this be done under 2 mins?

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by heshamelaziry » Tue Nov 03, 2009 3:17 pm
If x = 100 and z = 0 still gives 0 ! I do not think that this is a good study question.

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by Stuart@KaplanGMAT » Tue Nov 03, 2009 3:23 pm
heshamelaziry wrote:If x = 100 and z = 0 still gives 0 ! I do not think that this is a good study question.
You're missing the point.

x=100 and z=0 still give 0, which is exactly why (A) doesn't have to be true; we can pick values that violate (A) and still satisfy the original equation.
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by life is a test » Tue Nov 03, 2009 8:29 pm
heshamelaziry wrote:So, the answer can be A or E !!!!! I think the question has a typo.
the ans is E. you can think of it another way:

z=xz

xz-z=0

z(x-1)=0 hence x=1 or z=0 must be true.