If x and y are different integers, both divisible by 3, then which is not necessarily true?  Select the correct option:  A) x^2 + y^2 is divisible by 3  B) x - y is divisible by 3  C) xy is divisible by 3  D) x + y is divisible by 3  E) x + y is divisible by 6
Let x = 3k and let y = 3j.   Then x+y = 3(k+j) and k+j could be even or odd.   Thus 3(k+j) is not necessarily divisible by 6.   The answer is x + y is divisible by 6.
<result>E</result>
If x and y are different integers, both divisible by 3, then which is not necessarily true?