Results 1 to 6 of 6

Math Help - integrate

  1. #1
    Newbie
    Joined
    Jul 2010
    Posts
    15

    integrate

    How can integrate the following

    <br /> <br />
dy/dx = ( 5x^3 + 7y + 5 )^2 <br /> <br />
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by TGASJOOL View Post
    How can integrate the following

    <br /> <br />
dy/dx = ( 5x^3 + 7y + 5 )^2 <br /> <br />
    Expand the square on the right giving you a sixth order polynomial in x, then integrate term by term

    CB
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jul 2010
    Posts
    15
    i forgot to mention

    i should use a substitution

    <br />
u =  ( 5x^3 + 7y + 5 )<br />

    Please help.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by CaptainBlack View Post
    Expand the square on the right giving you a sixth order polynomial in x, then integrate term by term

    CB
    Since there is a term with y in it on the right hand side, it's possible that the real question is not to integrate but to solve a differential equation. The OP will need to clarify the situation.

    Quote Originally Posted by TGASJOOL View Post
    i forgot to mention

    i should use a substitution

    u = ( 5x^3 + 7y + 5)

    Please help.
    See my remark above.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by TGASJOOL View Post
    i forgot to mention

    i should use a substitution

    <br />
u =  ( 5x^3 + 7y + 5 )<br />

    Please help.
    In which case differentiate then you have:

    \dfrac{du}{dx}=15x^2+7\dfrac{dy}{dx}=15x^2+7u^2

    or:

    \dfrac{du}{dx}-7u^2=15x^2

    which you need to solve

    CB
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor

    Joined
    Apr 2005
    Posts
    16,210
    Thanks
    1789
    Quote Originally Posted by TGASJOOL View Post
    i forgot to mention

    i should use a substitution

    <br />
u =  ( 5x^3 + 7y + 5 )<br />

    Please help.
    No, you shoudn't. Since there is no "du" already in the integrand, it is far easier to just multiply it out and integrate the polynomial as Captain Black first said.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Integrate 3 e^x
    Posted in the Calculus Forum
    Replies: 4
    Last Post: June 9th 2010, 02:16 PM
  2. how to integrate this ??
    Posted in the Calculus Forum
    Replies: 8
    Last Post: August 9th 2009, 09:14 PM
  3. Integrate
    Posted in the Calculus Forum
    Replies: 7
    Last Post: April 28th 2009, 08:54 PM
  4. How to integrate x^x?
    Posted in the Calculus Forum
    Replies: 5
    Last Post: April 25th 2009, 08:51 PM
  5. Integrate
    Posted in the Calculus Forum
    Replies: 8
    Last Post: April 15th 2009, 04:50 PM

Search Tags


/mathhelpforum @mathhelpforum