How do you conclude from n≡4(mod9) that 9|n ?Let n∈Z. Prove the statement
If n≡4 mod 9, then n^2≡7 mod 9
So what I did was:
Proof: Assume that n≡4(mod9). Then 9|n and so n= 9q for some integer. Since n^2=81q^2=7(7q^2) is an integer, n^2 ≡7 mod 9
So could this possibly work?
No.9|4n would make it work Dr. Peterson?