# X^4/y^2 is the problem I am stuck on

x^4/y^2 +y^4/x^2+2xy : this is giving me a lot of problems. I believe I can use quad_over lin to solve this, but am unsure. Of course, I believe that there’s some factorization going on here. I do know it is convex. Any pointers appreciated here.

Perhaps `x^4/y^2 + y^4/x^2 + 2*x*y` is convex, but I haven’t proven it. Please show us your proof. bonus points if its constructive using CVX (DCP) building blocks. if your proof is constructive, that can be a guide for the CVX formulation.

If it is convex, it may take another poster more clever than me to provide a CVX reformulation.

x^4/y^2 +y^4/x^2+2xy = (x^2/y+y^2/x)^2. It’s a composition of quad_over_lin and g(u,v)=(u+v)^2 , which is convex and non-decreasing. Therefore if x,y>0, this problem can be solved by minimizing
`pow_pos(quad_over_lin(x, y) + quad_over_lin(y, x), 2)`. Note that `pow_pos(,2)` instead of `power(,2)` should be used here.

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@Gengchen-Wei Very nice.

In this case it is a little simpler to use `square_pos(...)` instead of `pow_pos(...,2)`