Assignment on Proofs

The method of exhaustion:	P 139: 17, 18.
Direct proofs:	P 139: 24, 25, 27, 28. P 146: 11, 12, 23
Prove or disprove: (direct proofs or disproofs by counterexample)	P 139: 1-3, 39 – 50. P 146: 13-15.
Indirect proofs by countraposition:	P 179: 17, 18, 20 b, 23b.
Proofs by contradiction:	P 179: 20 a, 23a. P 184: 3 – 12.
Proofs by cases:	Read Theorem 3.4.3 on page 162. P 164: 38.
Existential proofs:	P 139: 4 – 10.
Disprove:	P 139: 11 – 13.
Find mistakes in a proof:	P 139: 34-36. P 146: 32, 34.