1. ## Classifying critical points

Hi all,

So I'm trying to work out an exam question, regarding finding the critical point of a function, fractions always cause me a headache in calculus questions.

so anyways, heres the function in question, I just need to find partial derivitives on it, and I'm struggling

xy+(4/x)+(2/y)

2. For something like that you could rewrite the equation as:

$xy+4x^{-1}+2y^{-1}$

Does that make it easier to find the partials?

3. Thanks!
But differentiating that, gives me
y-4x^-2
and
x-2y^-2.
Usually i have to do a simultaneous equation from that point, but how do i when i have these ^-2's getting in my way? I just get tangled up here