q)
is true, we assume that p is true and use that to show that q must also be true.2. The question can be rewritten as an if--then statement. If r and
s are two rational numbers, then the product r·s must be a rational number. To prove that
an if--then statement (p q)
is true, we assume that p is true and use that to show that q must also be true.
Proof Suppose r and s are rational
numbers. Then by definition of rational, r = a/b and s = c/d for some integers a, b, c and d, where b 
0 and d
0
To prove that the product r·s is a rational number, multiply out the expressions we have for r and s.