) Prove or disprove: The sum of two odd numbers is even.

p.278, icon at Example 6 #2. Suppose the odd primes 3,5,7, 11, 13, 17, ... in order of increasing size are P1, P2, P3 · Prove or disprove: PiPi+1 +2 is prime, for all i ≥ 1.

#2

HELLP   The statement is false is equivalent to its negation is true by giving an example . The negation is: ∃x in D such that P(x) ∧ ~Q(x) The above would be used via:     proof by counterexample     proof by exhaustion     proof by manipulation     proof by induction