Results 1 to 4 of 4

Math Help - TI-89 Integrating Incorrectly

  1. #1
    Member RedBarchetta's Avatar
    Joined
    Apr 2008
    From
    United States
    Posts
    114

    TI-89 Integrating Incorrectly

    This is what my calculator is giving me:

    <br />
\int {\cos (1 - x)dx = \sin (x - 1)} <br />

    This is obviously wrong. Could anyone explain why it's doing this?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Moo
    Moo is offline
    A Cute Angle Moo's Avatar
    Joined
    Mar 2008
    From
    P(I'm here)=1/3, P(I'm there)=t+1/3
    Posts
    5,618
    Thanks
    6
    Hello,
    Quote Originally Posted by RedBarchetta View Post
    This is what my calculator is giving me:

    <br />
\int {\cos (1 - x)dx = \sin (x - 1)} <br />

    This is obviously wrong. Could anyone explain why it's doing this?
    I'm finding it correct

    It's just that -sin(x)=sin(-x) and hence the result
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member
    Joined
    Jun 2008
    Posts
    792
    It is not wrong.

    \int \cos{(1-x)} dx = -\sin{(1-x)} = \sin{(-(1-x))} = \sin{(x-1)}

    Recall that Sine is an odd function:
    \sin{(-u)} = -\sin{u}
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member RedBarchetta's Avatar
    Joined
    Apr 2008
    From
    United States
    Posts
    114
    I didn't notice the change from (1-x) to (x-1)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Have I been calculating our bills incorrectly?
    Posted in the Business Math Forum
    Replies: 3
    Last Post: November 8th 2011, 05:24 AM
  2. Did I differentiate this incorrectly?
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 4th 2010, 08:30 PM
  3. Replies: 0
    Last Post: January 14th 2010, 05:45 AM
  4. help with calc what am i doing incorrectly
    Posted in the Calculus Forum
    Replies: 1
    Last Post: September 16th 2009, 07:45 PM
  5. New to Integrating, I need a lot of help
    Posted in the Calculus Forum
    Replies: 32
    Last Post: April 27th 2008, 12:34 AM

Search Tags


/mathhelpforum @mathhelpforum