Results 1 to 8 of 8
Like Tree3Thanks
  • 1 Post By romsek
  • 1 Post By SlipEternal
  • 1 Post By SlipEternal

Math Help - Graph of differential equations?

  1. #1
    Member
    Joined
    Feb 2014
    From
    USA
    Posts
    231

    Graph of differential equations?

    I have this question:Graph of differential equations?-capture1.jpg Is my answer correct? I came to this answer because I actually worked each out to find c1 and then graphed them. When I graphed the second one y became negative while x, (t), went to infinity. This is an electronic version of this graph: Graph of differential equations?-capture1.2.jpg Oh, and I found that c1 for option 2 was (-8.46). The other options didn't turn out like this for their graph, but it could've been a mistake in a number of different steps. Is my answer right? Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Nov 2013
    From
    California
    Posts
    2,648
    Thanks
    1060

    Re: Graph of differential equations?

    no that's not correct
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Feb 2014
    From
    USA
    Posts
    231

    Re: Graph of differential equations?

    Quote Originally Posted by romsek View Post
    no that's not correct
    Could you tell me why it's not correct?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Nov 2013
    From
    California
    Posts
    2,648
    Thanks
    1060

    Re: Graph of differential equations?

    Quote Originally Posted by canyouhelp View Post
    Could you tell me why it's not correct?
    Graph of differential equations?-clipboard01.jpg

    it doesn't exhibit the desired behavior
    Thanks from canyouhelp
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Joined
    Nov 2010
    Posts
    1,930
    Thanks
    782

    Re: Graph of differential equations?

    If $k<0$, then as $t \to \infty$, $y \to a$.
    If $k>0$, then as $t \to \infty$, $e^{kt} \to \infty$, so if you want $y \to -\infty$, you need $Ae^{kt} \to -\infty$, so $A<0$. Which of the choices offers $k>0$ and $A<0$? As the problem says, you must solve for $A$ in each case.
    Last edited by SlipEternal; April 7th 2014 at 11:31 AM.
    Thanks from canyouhelp
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Feb 2014
    From
    USA
    Posts
    231

    Re: Graph of differential equations?

    Quote Originally Posted by romsek View Post
    Click image for larger version. 

Name:	Clipboard01.jpg 
Views:	5 
Size:	16.3 KB 
ID:	30630

    it doesn't exhibit the desired behavior
    Okay, then I believe option 4 is right?
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor
    Joined
    Nov 2013
    From
    California
    Posts
    2,648
    Thanks
    1060

    Re: Graph of differential equations?

    Quote Originally Posted by canyouhelp View Post
    Okay, then I believe option 4 is right?
    yes
    Follow Math Help Forum on Facebook and Google+

  8. #8
    MHF Contributor
    Joined
    Nov 2010
    Posts
    1,930
    Thanks
    782

    Re: Graph of differential equations?

    Quote Originally Posted by canyouhelp View Post
    Okay, then I believe option 4 is right?
    Correct.
    Thanks from canyouhelp
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: March 17th 2013, 08:47 PM
  2. Replies: 0
    Last Post: February 13th 2013, 09:12 AM
  3. Replies: 2
    Last Post: May 18th 2009, 03:49 AM
  4. Replies: 5
    Last Post: July 16th 2007, 04:55 AM
  5. Replies: 3
    Last Post: July 9th 2007, 05:30 PM

Search Tags


/mathhelpforum @mathhelpforum