Need clarification on a simple concept!!

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Need clarification on a simple concept!!

by manred » Mon Jul 09, 2007 9:11 pm
This is a DS question from PR Math Bin 1.

What is the value of x?

(1) x^2 = 4x (^ is my representation of to the power of)
(2) x is an even integer.

The choice are standard DS choices.

My answer was (C) BOTH statements together are sufficient but NEITHER statement alone is sufficient.

My solution is as follows:

x^2 = 4x
x^2 - 4x =0
x(x-4) = 0

So x=0 or x=4. So (1) alone not sufficeint.

(2) alone not sufficent.

Combining (1) and (2) we can get the value of x as 4, since zero (0) is neither even nor odd. So my answer was (C).

But the book says the answer is (E) Statements (1) and (2) TOGETHER are NOT sufficient.

All the calculations in the book were similar and it boils down to x=4 and x=0. But book says both 4 and 0 are even, so combining both is also not sufficient to determine the value of x.

As far as my knowledge goes 0 is neither even not odd. But the book says 0 is even. this was quite surprising for me. Is it GMAT Math?? or a mistake by PR guys.

Need clarification form u guys

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Search doesnt clarify

by manred » Mon Jul 09, 2007 9:32 pm
I have done some search on the web and still the ocnfusion remains. Some resources say that zero is even and the others claim it is neither even nor odd. But the majority says its even.

Yes, zero has been a topic of debate for mathematicians since ages and still is. But right now Iam only concerned about what the mathematicians at GMAC think about Zero. Guys anyone sure what GMAC thinks about Zero?

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Re: Search doesnt clarify

by gabriel » Mon Jul 09, 2007 11:29 pm
manred wrote:I have done some search on the web and still the ocnfusion remains. Some resources say that zero is even and the others claim it is neither even nor odd. But the majority says its even.

Yes, zero has been a topic of debate for mathematicians since ages and still is. But right now Iam only concerned about what the mathematicians at GMAC think about Zero. Guys anyone sure what GMAC thinks about Zero?
.. any number of the form 2*x is considered to be even ..x can take any whole number value .. using this defnition of an even number 0 is always considered to be even ..

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by discreet » Tue Jul 10, 2007 5:34 am
Maths cannot be different for GMAT :wink:
The concepts remain the same everywhere.

Note : Zero is neither positive nor negative.I guess you twisted it to neither even nor odd :)

Zero is an even number\integer....To confirm what GMAC thinks....

Refer OG 11 - Page number 108

It says ..... "0,2,4,6.... are consecutive even integers"

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by manred » Tue Jul 10, 2007 5:59 pm
thanks everybody for the clarification. Just a note that a few resources on the internet claim zero to be neither even nor odd. They have their own valid reasoning which cannot be ignored though.