Is (x-y)*(x+y) an even integer? (1) x and y are integers (2)

Question

Is (x-y)*(x+y) an even integer?

(1) x and y are integers
 (2) (x+y) is even

ykaiim · Answer

I marked B.
If x+y is even then whatever the value of x and y, the stated exp in question will be even.

Can someone explain why C is correct?

Bunuel · Answer

Answer is C because if x and y are not integers (second statement does not state that), then x+y may be even (statement 2) and (x-y)*(x+y) may not be an integer at all.

Example: 
x=1.8 and y=0.2 - answer to the question NO.
x=1.5 and y=0.5 - answer to the question YES.

Statement (1) says that x and y are integers so combined statements guarantee (x-y)*(x+y) being even.

Hope it helps.

neoreaves · Answer

yes agreed it should be C because x and y can be fractions

kratos0906 · Answer

Is 0 considered an even integer on GMAT?

My thought process:

if x=4, y=2 then, (x+y)*(x-y) is even. 
if x=2, y=2 then, (x+y)*(x-y) is 0.

So if 0 is not even, then answer could be E and if 0 is even, then answer should be C.

Is (x-y)*(x+y) an even integer? (1) x and y are integers (2)

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Is (x-y)*(x+y) an even integer? (1) x and y are integers (2)

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