here is what I am trying to do!

R=ln(u^2 + v^2 + w^2)

u= (x+2y)

v=(2x-y)

w=(2xy)

find deltaz/deltax and deltaz/deltay when x=y=1

This is a chain rule case correct? So:

Dr/dx=(1/((x+2y)^2+(2x-y)^2+(2xy)^2))(2(x+2y)(1)+2(2x-y)(2)+2(2xy)(2y))

Then placing 1 in all x and y makes:

Dr/dx=(14/9)?

And another one is:

let x^2 +y^2 +z^2=3xyz

find dz/dx and dz/dy

for this do I isolate z and then find dz/dx and dz/dy?

thanks!