can anyone explain me the solution and the logic behind odds and even numbers..
thank you.
thank you.
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Here it goes
From the statement we know either ( xy - odd, z - even ) or (xy even, z - odd)
a) One says : xy + xz = even.
Doesnt help, coz it could be xy and xz are both even, or are both odd
b) y + xz - odd : Doesnt help because, either y is odd and x is even or x is odd and y is even
combining both of them ( lets add the two of them up )
2(xy) + y(x+1 ) is odd ( odd + even = odd )
2xy is most definetly even, so Y(x+1) is most definetly odd [ since the only way we get an odd sum is o+e or e+o - all other combinations give an even sum)
so Y(x+1) = odd - now, the only way we get an odd product is odd X odd so X+1 = odd therefore X = even
QED
Anyone with a better method? I know mine is wayy to long to sit and do in the Gmat
Also, is there a shortcut for doing such problems ( i constantly find my self writing O+E = O and so on... then find the possible results - consumes a hell lot of time )
