Results 1 to 3 of 3

Thread: Substituting f(x)

  1. #1
    Newbie
    Joined
    Jun 2009
    Posts
    12

    Substituting f(x)

    I know this is really basic why does

    $\displaystyle
    f(2)=-4{x}^{-1}$

    equal

    $\displaystyle
    -2$

    and not

    $\displaystyle -8$
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    12,880
    Thanks
    1946
    Quote Originally Posted by Envy View Post
    I know this is really basic why does

    $\displaystyle
    f(2)=-4{x}^{-1}$

    equal

    $\displaystyle
    -2$

    and not

    $\displaystyle -8$
    Your question does not make any sense.


    Are you asking:

    If $\displaystyle f(x) = -4x^{-1}$ what does $\displaystyle f(2)$ equal?


    Let $\displaystyle x = 2$.


    You would have $\displaystyle f(2) = -4(2)^{-1}$

    $\displaystyle = -4\left(\frac{1}{2}\right)$

    $\displaystyle = -2$.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Apr 2009
    Posts
    136
    Awards
    1
    Substituting 2 into the equation



    -4 * ( 2 to the power of -1 )

    2 to the power of -1 is the same as 1 / 2

    so -4 * 1/2 = -2 and not -8
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Substituting equation
    Posted in the Pre-Calculus Forum
    Replies: 8
    Last Post: Apr 28th 2011, 11:00 PM
  2. Help substituting !
    Posted in the Differential Equations Forum
    Replies: 3
    Last Post: Apr 17th 2010, 05:24 PM
  3. Substituting
    Posted in the Differential Equations Forum
    Replies: 3
    Last Post: Oct 6th 2009, 02:29 PM
  4. Substituting in Sin^-1 relationship
    Posted in the Trigonometry Forum
    Replies: 6
    Last Post: Jan 18th 2009, 12:17 PM
  5. Substituting numbers into an integral.
    Posted in the Calculus Forum
    Replies: 8
    Last Post: Sep 1st 2008, 03:34 AM

Search Tags


/mathhelpforum @mathhelpforum