# partial derivative

• Mar 28th 2006, 12:27 PM
jedoob
partial derivative
Can someone pls tell me what the x partial derivative of:

(25-(x^2)-(y^2))^(1/2) is and how you would go about working it out.
• Mar 28th 2006, 12:36 PM
jedoob
all ok
it's ok - i worked it out.
• Mar 28th 2006, 12:46 PM
TD!
Are you sure? If you want we can check your answer if you post it :)
• Mar 28th 2006, 07:49 PM
ThePerfectHacker
Quote:

Originally Posted by jedoob
Can someone pls tell me what the x partial derivative of:

(25-(x^2)-(y^2))^(1/2) is and how you would go about working it out.

Let me just post the answer so you can check with mine.
$z=\sqrt{25-x^2-y^2}$ consider $y$ a constant because you need to find $\frac{\partial z}{\partial x}$.
Thus, by the chain rule,
$\frac{1}{2}\cdot (-2x)(25-x^2-y^2)^{-1/2}$
Thus,
$-\frac{x}{\sqrt{25-(x^2+y^2)}}$