Answer:
Any integer x can be represent in form of 3k, 3k+1, or 3k + 2 (k is integer).
Case 1: x = 3k => x^2 - 2 = 9k^2 - 2, which will not be divisible by 3
(notice that 2 is not divisibble by 3, but 9k^2)
Case 2: x = 3k + 1 => x^2 - 2 = 9k^2 + 6k + 1 - 2 = 9k^2 + 6k - 1, which will not be divisible by 3
(notice that 1 is not divisibble by 3, but 9k^2 + 6k)
Case 3: x = 3k + 2 => x^2 - 2 = 9k^2 + 12k + 4 - 2 = 9k^2 + 12k - 2, which will not be divisible by 3
(notice that 2 is not divisibble by 3, but 9k^2 + 12k)
=> x^2 - 2 will never be divisible by 3
Hope this helps!
:)
