implicit differentiation

freetofu

1. The problem statement, all variables and given/known data
Determine dy/dx
xy^-2 = 1

2. Relevant equations


3. The attempt at a solution
Here's what I tried:
y^-2 - 2xy^-3(dy/dx) = 1
dy/dx = (y - y^3)/2x

The answer in the book is y/2x. How do you do it?

rock.freak667

You differentiated the left side but not the right side

d/dx(1) = ?

freetofu

Thanks. Duh.