Results 1 to 4 of 4

Math Help - combining powers with trigonometry functions

  1. #1
    Member
    Joined
    Jul 2011
    Posts
    80

    combining powers with trigonometry functions

    Hi

    A solution to a problem i have is;

    x^4.sinx+4x^3.cosx

    does this simplfy to

    sinx^5 + 12cosx^4

    advice appreciated
    John
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Santa Cruz, CA
    Posts
    2,844
    Thanks
    3

    Re: combining powers with trigonometry functions

    Quote Originally Posted by celtic1234 View Post
    Hi

    A solution to a problem i have is;

    x^4.sinx+4x^3.cosx

    does this simplfy to

    sinx^5 + 12cosx^4

    advice appreciated
    John
    No, because x^4 and \sin x are two completely different functions; thus, it's a no-no to carry the x^4 term inside the sine function. To avoid such confusion, I would write it like x^4\sin(x)+4x^3\cos(x).
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jul 2011
    Posts
    80

    Re: combining powers with trigonometry functions

    thank you
    this site is a god send.
    John
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,319
    Thanks
    1238

    Re: combining powers with trigonometry functions

    You could simplify this by taking out a common factor though.

    \displaystyle x^4\sin{(x)} + 4x^3\cos{(x)} = x^3\left[x\sin{(x)} + 4\cos{(x)}\right]
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Combining 2 Functions
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: January 4th 2010, 05:11 PM
  2. Combining 2 Functions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 4th 2010, 05:11 PM
  3. combining functions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: June 22nd 2009, 02:33 AM
  4. Combining Functions
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: January 31st 2009, 06:47 PM
  5. combining functions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 19th 2008, 11:03 AM

Search Tags


/mathhelpforum @mathhelpforum