Thread: I am dealing with a problem and I hope you can help me

Hi all. I am dealing with a problem and I hope you can help me. I have already proved this:

Let us suppose that integers m and n can be written as sum of squares of two integers. Prove that m*n can also be written as sum of squares of two integers.


Now I am trying to prove this:Let us suppose that integers m and n can be written as sum of squares of four integers. Prove that m*n can also be written as sum of squares of four integers.


Can you help me on this?
Thank You for reading my post.

Originally Posted by Panarit

Let us suppose that integers m and n can be written as sum of squares of two integers. Prove that m*n can also be written as sum of squares of two integers.

Suppose that

Now show that