5. Use the method of proof by contrapositive to prove that if $a^2 - 2a + 7$ is even then $a$ is odd.
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The original statement is: If a - 2a + 7 is even, then a is odd. The negation of the original statement is: If a is not odd, then a - 2a + 7 is not even. To prove this, we assume that a is not odd, which means a is even. We can write a as a = 2k, where k is an Show more…
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