1. Oct 12, 2008

### Nachore

1. The problem

2. Relevant equations

I used z = (x)^(1/2) + (y)^(1/2)

3. The attempt at a solution

What I used:
let z = (x)^(1/2) + (y)^(1/2)
x = 25
y = 10
dx = 0.5
dy = 0.5
Using .
I plugged in 1/(2(x)^(1/2)) for the partial derivative w/respect to x, and 1/(2(y)^(1/2)) for the partial derivative w/respect to y. When I plug into the formula, I get 0.1290 not 8.0139 like in the calculator. What am I doing wrong?

Last edited: Oct 12, 2008
2. Oct 12, 2008

### HallsofIvy

Staff Emeritus
You the did the derivative wrong. The derivative of xn is n xn-1, not n xn as you have.