Proofs Homework Help?

Question

Prove:
If n is odd, then n^2 = 8k + 1

{I know an odd number can be defined as 2k +1, where k is any interger.}

I need a little assistance. Thank you.

Just as FYI, this question was stated word for word so the question itself cannot be altered.

Answer 1

Can't prove it as n cannot = + or -1 and k be an interger.
It appears to work with other odd integers. Change your question then it may be possible to prove it.