1. The problem statement, all variables and given/known data Hi everyone. I'm studying a problem and I need to prove that I have a basis. I tryed a proof and to achieve it I need to show that : if k divides a*b and also divides a2 +2*b2 Then k divides both a and b. 2. Relevant equations I'm not sure what I'm asserting is true but if it was, then it would be great for me ( cause my proof would be finished). I first thought that if k divided a sum then it divided every term of that sum but I understood it was wrong (the other way is correct). I'm taking any idea!