can someone help me out with this

Discussion in 'Differential Equations' started by isaac a, Mar 16, 2013.

  1. isaac a

    isaac a

    Joined:
    Mar 16, 2013
    Messages:
    1
    Likes Received:
    0
    xy multiply by DY/DX=y squared+4
     
    isaac a, Mar 16, 2013
    #1
  2. isaac a

    HallsofIvy

    Joined:
    Nov 6, 2021
    Messages:
    160
    Likes Received:
    78
    In other words dy/dx= y^2+ 4. You can write it as dy/(y^2+ 4)= dx and integrate.

    On the left, you might find it simplest to factor "4" out of the denominator write
    (1/4) d/((y/2)^2+ 1)= dx or d/((y/2)^2+ 1)= 4dx.

    To make it even easier, let u= y/2 so that du= dy/2, 2du= dy and the equation becomes
    2du/(u^2+ 1)= 4dx.

    du/(u^2+ 1) = 2x.
    Integrate!
     
    Last edited: Nov 7, 2021
    HallsofIvy, Nov 7, 2021
    #2
    nycmathguy likes this.
  3. isaac a

    nycmathguy

    Joined:
    Jun 27, 2021
    Messages:
    5,386
    Likes Received:
    422
    Your LaTex did not form adequately. Check out your answer.
     
    nycmathguy, Nov 7, 2021
    #3
  4. isaac a

    HallsofIvy

    Joined:
    Nov 6, 2021
    Messages:
    160
    Likes Received:
    78
    xy dy/dx= y^2+ 4

    ydy/(y^2+ 4)= dx/x

    Integrate
     
    HallsofIvy, Nov 18, 2021
    #4
  5. isaac a

    nycmathguy

    Joined:
    Jun 27, 2021
    Messages:
    5,386
    Likes Received:
    422
    Glad you joined this site. We need more math people like you and MathLover1. Your username is familiar to me. Are you the guy from mathhelpforum.com? How about freemathhelp.com? What about mathforums.com? What about mathhelpboard.com? Are you Dan?
     
    nycmathguy, Nov 18, 2021
    #5
  6. isaac a

    HallsofIvy

    Joined:
    Nov 6, 2021
    Messages:
    160
    Likes Received:
    78
    Yes, I am on all of those. No, I am not Dan.
     
    HallsofIvy, Nov 19, 2021
    #6
    nycmathguy likes this.
  7. isaac a

    nycmathguy

    Joined:
    Jun 27, 2021
    Messages:
    5,386
    Likes Received:
    422
    I left the groups listed above months ago. Lots of people are immature, always pressing for me to learn LaTex and/or show work. I show my work when I know how to get started and/or if I understand the question. I miss MarkFL. What a great math mind he is.
     
    nycmathguy, Nov 19, 2021
    #7
  8. isaac a

    HallsofIvy

    Joined:
    Nov 6, 2021
    Messages:
    160
    Likes Received:
    78
    Wow! People are "immature" because they expect you to abide by the rules you agreed to when you joined the board. I am wondering why you would be trying to do problems that you don't "know how to get started". Whoever gave you the problem, perhaps a teacher, clearly expects you to know how to get started. If you don't, ask them first. And if you do not "understand the question" ask for an explanation of the question, not for the solution!
     
    HallsofIvy, Nov 19, 2021
    #8
  9. isaac a

    nycmathguy

    Joined:
    Jun 27, 2021
    Messages:
    5,386
    Likes Received:
    422
    1. I guess you remember me.

    2. I like writing out the solution on paper and then uploading to the forum. What's so bad about that?

    3. I am not in a formal classroom. I am reviewing math learned long ago. My last official math class was in the Spring 1993 semester.

    4. You are right about asking for help with questions that are beyond my level or that I have not made an effort to learn. This is a big mistake on my part.

    5. Asking for an explanation of the question makes sense to me. I rarely ask for the solution. I do ask for hints, a few steps, to rephrase the question, etc.

    6. I'd rather try to solve a problem on my own, even if I get it wrong, which is what I have been doing on this site.

    7. Is there anything else I should know in terms of learning math outside the classroom experience?
     
    nycmathguy, Nov 19, 2021
    #9
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads
There are no similar threads yet.
Loading...