Hey guys,

I've got a problem which shouldn't be too tricky, but for some reason I can't quite get it.2

I want to prove that x^{2}-2xy+3y^{2}>= 0

I can see that this is true because x^{2}+3y^{2}will always be larger than 2xy, but I am not sure how to formalise it as a proof. This is something I often struggle with :\