# Homework Help: Supremum problem

1. Jan 26, 2012

### Ted123

1. The problem statement, all variables and given/known data

What is

$$\displaystyle \sup_{\substack{x\in [-1.7,1.4] \\ y\in\mathbb{R} }} \frac{2.6xy}{(y^2+1)^2}$$
(the supremum of $\displaystyle \frac{2.6xy}{(y^2+1)^2}$ over $x\in [-1.7,1.4]$ and $y\in\mathbb{R}$)?

3. The attempt at a solution

How do I find the least upper bound?

Last edited: Jan 26, 2012
2. Jan 26, 2012

### susskind_leon

Re: Supremum

Think about it: If you have a function type h(x,y)=f(x)*g(y). How would you find its maximum?