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Homework Help: Confused on what u do next with an exact equation, Diff EQ

  1. Jan 30, 2006 #1
    Hello everyone. We just started working with exact equations and i'm confused on what I do next! here is the problem:
    Use the "mixed partials" check to see if the following differential equation is exact.
    If it is exact find a function F(x,y) whose level curves are solutions to the differential equation
    http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/71/5a4f0007c2fd2947228eee9825b55d1.png [Broken]
    http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/8d/8616ca1dd6ce230911485b98a57fa31.png [Broken]

    Here is my work, I submitted:
    2*y^2+2*x^2-4 which was wrong.

    WOrk:
    http://img206.imageshack.us/img206/6632/lastscan3tp.jpg [Broken]

    Thanks!
     
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Jan 30, 2006 #2
    your int of 2xy^2 + 4y is incorrect
     
  4. Jan 31, 2006 #3

    HallsofIvy

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    Science Advisor

    And what, again, is [itex]\int (2xy^2+ 4y)dx[/itex]?

    Did you forget that you were integrating, not differentiating?
     
  5. Jan 31, 2006 #4
    Thanks everyone! yeah I don't know what i was thinking! I got:
    http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/8d/8616ca1dd6ce230911485b98a57fa31.png [Broken]http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/8b/ad397009ac98a90c5581831292c16e1.png [Broken]
    Which is right! weee!
     
    Last edited by a moderator: May 2, 2017
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