Results 1 to 8 of 8

Math Help - Find range of values

  1. #1
    Senior Member
    Joined
    Jul 2009
    From
    Singapore
    Posts
    338

    Find range of values

    find the range of values for k for which the function
    \frac{x^2-1}{(x-2)(x+k)}
    where x is real, takes all real values.
    I don't know how to start. Any pointers?
    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Oct 2009
    Posts
    218
    The question asks you for what values of X, would F(x) exist. Or what values of X would F(x) not exist.

    Hint: C/0 doesn't exist (where C is an arbitrary constant).
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Jul 2009
    From
    Singapore
    Posts
    338
    so x cannot be 2 or -k. i dont know what else the answer is |k|\leq 1
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Oct 2009
    Posts
    218
    Sorry, I misread the question. I thought you were supposed to find values for x instead of k.

    So same as idea as before. We know that k cannot be -x and we also know that x can't be 2. Therefore, k cannot be -2 (I think).
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Senior Member
    Joined
    Jul 2009
    From
    Singapore
    Posts
    338
    ok got that, but how to continue confuses me
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Oct 2009
    Posts
    218
    What part are you confused about? You know that k can't be -x, and when x = 2, k can't be -2.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Senior Member
    Joined
    Jul 2009
    From
    Singapore
    Posts
    338
    yes, i meant how to find the values of k other than that it isn't -2.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Member
    Joined
    Oct 2009
    Posts
    218
    The domain for is k (- \infty, -x)\cup(-x, \infty)
    The domain of x is (- \infty, -2)\cup(-2, \infty)
    Last edited by statmajor; November 4th 2009 at 07:34 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: June 1st 2011, 01:47 AM
  2. Find the range of values of x
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: May 7th 2011, 10:31 AM
  3. Find range of positive values of x?
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 13th 2009, 10:42 PM
  4. Range values
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: November 6th 2008, 03:34 AM
  5. Range values
    Posted in the Algebra Forum
    Replies: 2
    Last Post: November 1st 2008, 08:12 AM

Search Tags


/mathhelpforum @mathhelpforum