Question

Prove that the square of an odd number is of the form 8k+1 g

Answer 1

Show that n is odd →∃m∈ℤ,n2=8m+1

Let k be an integer so that n=2k+1. Then n2=(2k+1)2=4k2+4k+1=2(2k2+2k)+1.

But this isn't equal to 8m+1, so can I change that into 4(2m)+1?