3. Recall that the negation of $ x such that " y, P(x,y) is " x, $ y such that ~P(x,y).
The negation of this statement is " x R, $ y
R such that xy
0.
The original statement
is true since there does exist a real number (x = 0) such
that for every real number y, xy = 0.
The negation is false since it does not hold when x = 0.