Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

ranyai12

  • one year ago

Evaluate the line integral 5ydx+2xdy where C is the straight line path from (4,4) to (7,8)

  • This Question is Closed
  1. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I got 276 but was wrong

  2. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Hero please help!

  3. SithsAndGiggles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\int_C (5y~dx+2x~dy)\] The line connecting (4,4) and (7,8) is \(y=\dfrac{4}{3}x-\dfrac{4}{3}\) Parameterize \(C\) by \[\begin{cases}x=t\\ \\ y=\dfrac{4}{3}t-\dfrac{4}{3}\\ \\ 4<t<7 \end{cases}\] So you have \(dx=dt\) and \(dy=\dfrac{4}{3}dt\): \[\int_4^7 \bigg[5\left(\dfrac{4}{3}t-\dfrac{4}{3}\right)~dt+2t~\left(\dfrac{4}{3}dt\right)\bigg]\\ \int_4^7\bigg[\frac{28}{3}t-\frac{20}{3}\bigg]~dt\\ ~~~~~~~~~~~~~~~~\vdots\]

  4. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    did you get 134?

  5. SithsAndGiggles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Yep: http://www.wolframalpha.com/input/?i=Integrate%5B%2828%2F3%29*t-%2820%2F3%29%2C%7Bt%2C4%2C7%7D%5D Can't guarantee that's the right answer, but that's what my method is getting, so I'm sticking with it.

  6. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    when i did it by hand, i ended up getting 288

  7. SithsAndGiggles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Could you show your work? It might be a mistake in the integration, or the parameterization.

  8. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    288 is wrong :(

  9. SithsAndGiggles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Well what did you do when you tried it? How did you parameterize \(C\)?

  10. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no i integrated wrong! the answer is indeed 134

  11. SithsAndGiggles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Oh ok then.

  12. ranyai12
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks so much

  13. SithsAndGiggles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    You're welcome!

  14. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

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.