- #1

One example could be f(x)= sqr(20-x^2-7y^2). I know yo treat the y as a constent, but I am horrible with my derv. Any help would be appreciated.

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- Thread starter Arden1528
- Start date

- #1

One example could be f(x)= sqr(20-x^2-7y^2). I know yo treat the y as a constent, but I am horrible with my derv. Any help would be appreciated.

- #2

StephenPrivitera

- 363

- 0

g'=-2x

So the partial derivative of f wrt x is,

f'=(-2x)/(2f(x))=-x/f(x)

Please forgive the sloppy notation.

- #3

Hurkyl

Staff Emeritus

Science Advisor

Gold Member

- 14,967

- 19

(d/dx) (u^n) = n u^(n-1) (du/dx)

then just plug in the right things for

- #4

You said, "I keep running into problems having square roots.

One example could be f(x,y)= sqr(20 - x^2 - 7y^2)"

Just where is your difficulty?

You know how to take

You know that a square root is a one-half power.

And you know the Chain Rule.

f(x,y) = (20 - x

Hence, f

And, f

- #5

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