Why is my derivative of sqrt(xy) with respect to y wrong?

[-EquinoX-]

Homework Statement

What is the derivative of sqrt(xy) with respect to y?

Homework Equations

The Attempt at a Solution

The sqrt(xy) is equal as (xy)^(1/2), so therefore what I have is 1/2 (xy) ^ -1/2, why is this wrong?

 

[quantumdude]

You've forgotten to use the Chain Rule. You have to differentiate the function inside the radical.