Results 1 to 4 of 4

Math Help - problems

  1. #1
    Newbie
    Joined
    Jun 2012
    From
    us
    Posts
    2

    problems

    Can anyone please help me with these problems?

    1. S((cosx(^3))sinx dx

    2. S(x+1)sin((x^2)+2x dx

    3. S(x^2)cos(x^3) dx

    Can anyone explain me how I can apply the Gini index? Or use the Gini index when it comes down to calculus?

    Thanks I appreciate it in advance.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Reckoner's Avatar
    Joined
    May 2008
    From
    Baltimore, MD (USA)
    Posts
    1,024
    Thanks
    75
    Awards
    1

    Re: problems

    I guess 'S' is being used as an integral sign? All of these require only simple substitution:

    Quote Originally Posted by stampmagnet View Post
    1. \int\cos^3x\sin x\,dx
    Let u = \cos x\Rightarrow du = -\sin x\,dx.

    Quote Originally Posted by stampmagnet View Post
    2. \int(x+1)\sin\left(x^2+2x\right)\,dx
    Let u = x^2 + 2x\Rightarrow du = 2x + 2\,dx.

    Quote Originally Posted by stampmagnet View Post
    3. \int x^2\cos x^3\,dx
    Let u = x^3\Rightarrow du = 3x^2\,dx.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jun 2012
    From
    us
    Posts
    2

    Re: problems

    Yes the S is the integral. But how can I integrate the cos's and the sin's?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor Reckoner's Avatar
    Joined
    May 2008
    From
    Baltimore, MD (USA)
    Posts
    1,024
    Thanks
    75
    Awards
    1

    Re: problems

    Quote Originally Posted by stampmagnet View Post
    Yes the S is the integral. But how can I integrate the cos's and the sin's?
    \int\sin u\,du = -\cos u + C

    \int\cos u\,du = \sin u + C

    The integration should be fairly straightforward after you make the substitutions. For example, take number 3. Using the substitution I stated earlier,

    \int x^2\cos x^3\,dx

    =\frac13\int3x^2\cos x^3\,dx

    =\frac13\int\cos u\,du

     = \frac13\sin u + C

     = \frac13\sin x^3 + C.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 0
    Last Post: April 2nd 2012, 04:11 PM
  2. Replies: 3
    Last Post: October 3rd 2011, 05:35 AM
  3. binomial problems/normal problems
    Posted in the Statistics Forum
    Replies: 1
    Last Post: October 19th 2010, 11:46 PM
  4. binomial problems as normal problems
    Posted in the Statistics Forum
    Replies: 1
    Last Post: October 19th 2010, 11:41 PM
  5. Problems with integration word problems
    Posted in the Calculus Forum
    Replies: 5
    Last Post: April 25th 2010, 05:39 PM

Search Tags


/mathhelpforum @mathhelpforum