Question 215857
if two numbers are odd, then thier sum is even 
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That shows it's true for 5 and 7, but not in general.
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Odd numbers can be expressed as 2n+1, where n is any integer (odd or even).
Another odd number is 2m+1, same stiputation.
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The sum of any 2 odd numbers is:
2n + 1
2m + 1
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Sum = 2(m+n) + 2
Whether the sum of m and n is odd or even, 2 times it is even.  Add 2, still even.