Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

kingdan1550 Group Title

How do I partially differentiate f = 2x/(x^2 +y^2) wrt x and y? Is it by the quotient rule? Any help is very much appreciated.

  • 2 years ago
  • 2 years ago

  • This Question is Closed
  1. experimentX Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    by treating one as constant

    • 2 years ago
  2. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    quotient rule needed for \(f_x\) but not for \(f_y\) since in that case you view \(2x\) as a constant

    • 2 years ago
  3. kingdan1550 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you

    • 2 years ago
  4. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    who nellie, you are differentiating not integrating.

    • 2 years ago
  5. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    \[f_x=\frac{(x^2+y^2)2-x^2(2x)}{(x^2+y^2)^2}\] then some algebra to clean it up

    • 2 years ago
  6. niki Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    thnxxxxxx

    • 2 years ago
  7. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    \(f_y\) is easier because you treat the numerator as a constant you get \[f_y=-\frac{2y}{(x^2+y^2)^2}\]

    • 2 years ago
  8. kingdan1550 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I ended up getting 2/(x^2 + y^2) - 4x^2/(x^2 +y^2)^2 for the partial derivative wrt x and -4yx/(x^2 +y^2) for y. Any idea where I might be going wrong? Thanks again

    • 2 years ago
  9. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    maybe i made a mistake. lets do it for \(f_y\)

    • 2 years ago
  10. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    oh right, doh you are rigth about \(f_y\)

    • 2 years ago
  11. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    well, except the denominator should be squared

    • 2 years ago
  12. kingdan1550 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Why is that?

    • 2 years ago
  13. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    quotient rule

    • 2 years ago
  14. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    or in this case just \[\frac{d}{dy}\frac{1}{f(y)}=-\frac{f'(y)}{f^2(y)}\]

    • 2 years ago
  15. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    first one it looks like you are using the product rule, so i might be the same as my answer

    • 2 years ago
  16. satellite73 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    oh yes, you are right. i missed a 2 from the 2x up top you are correct

    • 2 years ago
  17. kingdan1550 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Ah, fantastic. Thanks a million.

    • 2 years ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.