Check whether the following pair of statements is negation of each other. Give reasons for the answer.
(i) x + y = y + x is true for every real numbers x and y.
(ii) There exists real number x and y for which x + y = y + x.
The negation of statement (i) is as follows.
There exists real number x and y for which x + y ≠ y + x. This is not the same as statement (ii).
Thus, the given statements are not the negation of each other.