Question

Prove that if n is an integer, these four statements are equivalent: (i) n is even, (ii) n 1 is odd, (iii) 3n 1 is odd, (iv) 3n is even.

Answer 1

Explanation:

Hello,

If n is even, it means that we can find k integer such that n = 2 * k.

Then n+1=2*k+1 is odd.

3n+1=6k+1=2*(3k)+1 where 3k is an integer so 3n+1 is odd.

3n = 2*(3k) is even.

Besides, if n+1 is odd we can find an integer p so that n+1=2p+1 so n = 2p is even.

3n+1 is odd means that we can find an integer q such that 3n+1=2q+1 so 3n=2q as 3 is not dividable by 2, it means that n is a multiple of 2, then n is even.

3n is even means that we can write 3n = 2z where z is an integer and again it means that n is a multiple of 2 and then n is even.

Thank you.