Can some one help?!!! Thank you so much!!!
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The key to this is finding the function that maps N to Z. Basically you want to map all the even numbers to the negative integers, and the odd numbers to 0 and the positive integers. So:
for all n = even, f(n) = -(n/2)
for all n = odd, f(n) = (n-1)/2
for all n E N.
Then just prove that your function f(n) is injective and surjective for the cases n = even, and n = odd!
for all n = even, f(n) = -(n/2)
for all n = odd, f(n) = (n-1)/2
for all n E N.
Then just prove that your function f(n) is injective and surjective for the cases n = even, and n = odd!