Results 1 to 5 of 5

Math Help - Solving Algebraic Fractions

  1. #1
    Newbie
    Joined
    Oct 2010
    Posts
    2

    Solving Algebraic Fractions

    I'm having to solve some algebraic fractions, which is like normal algebra, but with fractions involved basically. I've got this:

    <br />
\frac{1}{x+1}+\frac{1}{x-1}=4<br />

    And through algebra, I've got to this (if you want to post the entire process of how I got to it, then please ask):

    <br />
2x^2-x-2=0<br />

    And I can't factorise this and solve it, nor does it work if I plug it into the quadratic formula, because I end up trying to square root a minus number (again, ask if you want to know how I got to it):

    <br />
x=\frac{1\pm\sqrt{-63}}{8}<br />

    Now, I wouldn't mind ending up with an in-solvable quadratic, but the question specifically states to SOLVE the equation, so I'm kind of stuck now. I've been over it several times, and given it to my Dad to have a try, and he got to the same stage that I did, and I'm pretty sure I haven't made a mistake (of course, it could just be a silly mistake that we both somehow made, but I think the chance of this is pretty low).
    I could wait to ask my teacher, but the point of this homework is to practice solving these, and to learn from mistakes I make, so if someone could see what the problem is, then could you help me?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by louis058 View Post
    I'm having to solve some algebraic fractions, which is like normal algebra, but with fractions involved basically. I've got this:

    <br />
\frac{1}{x+1}+\frac{1}{x-1}=4<br />

    And through algebra, I've got to this (if you want to post the entire process of how I got to it, then please ask):

    <br />
2x^2-x-2=0<br />

    And I can't factorise this and solve it, nor does it work if I plug it into the quadratic formula, because I end up trying to square root a minus number (again, ask if you want to know how I got to it):

    <br />
x=\frac{1\pm\sqrt{-63}}{8}<br />

    Now, I wouldn't mind ending up with an in-solvable quadratic, but the question specifically states to SOLVE the equation, so I'm kind of stuck now. I've been over it several times, and given it to my Dad to have a try, and he got to the same stage that I did, and I'm pretty sure I haven't made a mistake (of course, it could just be a silly mistake that we both somehow made, but I think the chance of this is pretty low).
    I could wait to ask my teacher, but the point of this homework is to practice solving these, and to learn from mistakes I make, so if someone could see what the problem is, then could you help me?
    Your quadratic equation is correct. The discriminant is (-1)^2 - 4(2)(-2) = ....
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2010
    Posts
    2
    Oh my gosh, you're right... I said the discriminant was -63 because I had took away 64 instead of adding it... Didn't look out for the signs .

    So it should be something like, I guess:
    <br />
x=\frac{1\pm\sqrt{17}}{4}<br />

    Thanks for the help!
    Last edited by mr fantastic; October 16th 2010 at 09:59 PM. Reason: d --> sh
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,102
    Thanks
    68
    Quote Originally Posted by louis058 View Post
    I said the discriminant was -63 because I had took away 64 instead of adding it...
    How did you come up with having to deal with 64 ?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Thread closed due to Moderator edits being undone by the poster.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Algebraic Fractions
    Posted in the Algebra Forum
    Replies: 3
    Last Post: May 9th 2011, 03:39 AM
  2. algebraic fractions
    Posted in the Algebra Forum
    Replies: 22
    Last Post: January 21st 2011, 09:44 PM
  3. Replies: 0
    Last Post: April 28th 2010, 09:53 AM
  4. algebraic fractions
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 1st 2009, 06:11 PM
  5. Algebraic fractions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 12th 2008, 11:57 PM

Search Tags


/mathhelpforum @mathhelpforum