odd +- odd = evennicajvch wrote:If x and y are positive integers, is the product xy even?
1) 5x-4y is even
2) 6x + 7y is even
even+- even = even
even+- odd = odd
IMH D
Evens
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Patrick_GMATFix
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The key to this is a good rephrase. For a product of 2 integers to be even, at least one of them must be even.
REPHRASE: Is x or y even?
The statements should be evaluated with even/odd in mind. For instance look at (1). 4y is always even. so 5x-4y is 5x-even. For this to have an even result, 5x itself must be even, so x must be even. This answers our rephrase with a definitive YES.
The 2nd statement should be handled the same way. Again, think in terms of even/odd property. The answer is D
This is GMATPrep question 1510
-Patrick
REPHRASE: Is x or y even?
The statements should be evaluated with even/odd in mind. For instance look at (1). 4y is always even. so 5x-4y is 5x-even. For this to have an even result, 5x itself must be even, so x must be even. This answers our rephrase with a definitive YES.
The 2nd statement should be handled the same way. Again, think in terms of even/odd property. The answer is D
This is GMATPrep question 1510
-Patrick
