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Answers
A
B
C
D
E
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Difficulty—
If m & n are positive integers, is n even ?
1) m(m +2) + 1 = mn
2) m(m + n) is odd
1) m(m +2) + 1 = mn
2) m(m + n) is odd
1. if m is odd, then m(m+2)+1 is even, then m(m+2)+1=nm must be even---> n is even
if m is even, then m(m+2)+1 is odd, and mn must be even. There is a contradiction, then m must be odd and n must be even.
sufficient
2. m(m+n) is odd, then m is odd, m+n is even---> n is even
sufficient
The correct answer is D!
