Sarahisme Posted October 10, 2005 Share Posted October 10, 2005 Hi all, i am having real difficulty doing this partial deriv. problem! would anyone be able to help me? (i am not even sure where to start really! ) Thanks Sarah Link to comment Share on other sites More sharing options...
Sarahisme Posted October 10, 2005 Author Share Posted October 10, 2005 well this is what i have done so far, but i don't really know what i am doing... z = f(x,y) and [math] r = \sqrt(x^2 + y^2) \implies y = \sqrt(r^2 - x^2)[/math] so z = [math] f(x, (r^2 - x^2)^{0.5})[/math] so [math] \frac{\partial z}{\partial x}|_r = \frac{\partial z}{\partial x} \frac{\partial x}{\partial x} + \frac{\partial z}{\partial y} \frac{\partial }{\partial x}(r^2 - x^2)^{0.5} [/math] [math] = \frac{\partial z}{\partial x} - \frac{\partial z}{\partial y} \frac{x}{(r^2 - x^2)^{0.5}}[/math] but yeah... now i'm stuck Link to comment Share on other sites More sharing options...
Sarahisme Posted October 10, 2005 Author Share Posted October 10, 2005 ok, wait i think i've got the first bit, but not the second bit of the question (adding the two) Link to comment Share on other sites More sharing options...
Sarahisme Posted October 15, 2005 Author Share Posted October 15, 2005 got it all now! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now