Prove the following using the Contrapositive, Proof by Cases, or Contradiction. 1. If m and n are integers of the same parity (both even or both odd), then 7m - 3n is even. 2. Let a, b Z. If ab is even, then a is even or b is even. 3. Suppose that a, b, c € Z and a divides b + c. Show that if a does not divide b, then a does not divide c.

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Author:Erwin Kreyszig
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Prove the following using the Contrapositive, Proof by Cases, or Contradiction.
1. If m and n are integers of the same parity (both even or both odd), then 7m - 3n is even.
2. Let a, b € Z. If ab is even, then a is even or b is even.
3. Suppose that a, b, c € Z and a divides b + c. Show that if a does not divide b, then a does
not divide c.
4. Let a, b € Z, and let p be a prime. If p does not divide ab, then p does not divide a and p
does not divide b.
5. There exists no integers j, k for which 18j + 6k = 1.
6. Suppose m, n E Z. Prove that if 4 divides m² + n², then m and n are both even.
Transcribed Image Text:Prove the following using the Contrapositive, Proof by Cases, or Contradiction. 1. If m and n are integers of the same parity (both even or both odd), then 7m - 3n is even. 2. Let a, b € Z. If ab is even, then a is even or b is even. 3. Suppose that a, b, c € Z and a divides b + c. Show that if a does not divide b, then a does not divide c. 4. Let a, b € Z, and let p be a prime. If p does not divide ab, then p does not divide a and p does not divide b. 5. There exists no integers j, k for which 18j + 6k = 1. 6. Suppose m, n E Z. Prove that if 4 divides m² + n², then m and n are both even.
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