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Re: Is (x-y)*(x+y) an even integer? [#permalink]
26 May 2011, 09:50

if your statement 1 means x and y are integers than

st-1 ==> not sufficient. x and y could be integer like x = 4 and y = 1 then (x+y)*(x-y) is odd integer and x =4 and y =2 makes the expression even integer st-2 ==>not sufficient; x+y just says even... we dont know if its integer.like x = 4 and y=0.2 then (x+y) * (x-y) is even number (but not integer) and x=4 and y=2 makes the expression even integer.

together we know x and y are integers and x+y is even so the exp wil be even integer.