Results 1 to 3 of 3

Math Help - should be simple, where am i going wrong?

  1. #1
    Newbie
    Joined
    Dec 2007
    Posts
    22

    should be simple, where am i going wrong?

    [(5)/(x-1) - ((2x)/(x+1))] - 1 is less than 0
    when I simplify (get common denom to subtract the 1), i get (-3x^2 + 7x + 6)/(x^2 - 1).
    i am assuming i am making an error in the simplification here, but i have checked 3 times. the answers in the back of the book (for zeros) are 1, -1 (from denom, i get this part) and -(2/3) and 3. it's these two i can not get from my numerator. where is my error???
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member 11rdc11's Avatar
    Joined
    Jul 2007
    From
    New Orleans
    Posts
    894
    \bigg[\frac{5}{x-1}-\frac{2x}{x+1}\bigg] -1 < 0


    \frac{5x + 5 -2x^2 + 2x -(x^2 -1)}{x^2 -1} < 0

    \frac{-3x^2 +7x +6}{(x+1)(x-1)} < 0

    Nope that is correct but you have to test and see in what intervals it would be positive and when it would be negative

    Look at this post you can use a chart like the one Moo used to see what is going on

    http://www.mathhelpforum.com/math-he...76-domain.html
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Dec 2007
    Posts
    22
    thanks for the response, thought i was losing my mind. i had checked it 3 times.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 5
    Last Post: March 2nd 2012, 03:57 PM
  2. simple integrating factors problem.. cant see what im doing wrong
    Posted in the Differential Equations Forum
    Replies: 2
    Last Post: April 30th 2011, 10:54 PM
  3. Replies: 2
    Last Post: March 28th 2010, 05:17 PM
  4. Replies: 3
    Last Post: January 26th 2010, 09:48 AM
  5. complex number simple (wrong thread)
    Posted in the Calculus Forum
    Replies: 5
    Last Post: June 14th 2009, 03:31 PM

Search Tags


/mathhelpforum @mathhelpforum