Results 1 to 5 of 5

Math Help - Polynomial Simplification

  1. #1
    Member
    Joined
    Mar 2010
    Posts
    150

    Polynomial Simplification

    First time poster here!

    I am reading through some calculus proofs on derivatives and I'm a little rusty on some of my algebra. Would someone mind helping me figure out the steps to go from #1 to #2?

    #1 (x+dx)^{-2}

    #2 x^{-2}*(1+\frac{dx}{x})^{-2}

    I would like to politely request a step by step answer if you wouldn't mind because i don't remember much about this from Algebra. You will not insult my intelligence. Thanks in advance for your help.

    -db
    Last edited by dbakeg00; March 4th 2010 at 11:29 AM. Reason: hit enter too soon
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Apr 2005
    Posts
    14,973
    Thanks
    1121
    Quote Originally Posted by dbakeg00 View Post
    First time poster here!

    I am reading through some calculus proofs on derivatives and I'm a little rusty on some of my algebra. Would someone mind helping me figure out the steps to go from #1 to #2?

    #1 (x+dx)^{-2}

    #2 x^{-2}*(1+\frac{dx}{x})^{-2}

    To \frac{1}{(x+ dx)^2}= \frac{1}{x^2+ 2x dx+ (dx)^2}
    Start buy factoring an "x" out of (x+ dx): since dx= x\frac{dx}{x} that is x(1+ \frac{dx}{x})

    Now take both to the -2 power: x^{-2}(1+ \frac{dx}{x})^{-2}



    I would like to politely request a step by step answer if you wouldn't mind because i don't remember much about this from Algebra. You will not insult my intelligence. Thanks in advance for your help.

    -db
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Mar 2010
    Posts
    150
    Thank you.

    I guess I never knew that <br /> <br />
dx= x\frac{dx}{x}<br />
...that must be why I couldn't see how you got from the first expression to the second. That helped a lot. Thank you again.

    db
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Mar 2010
    Posts
    150
    Anyone care to explain why <br /> <br />
dx= x\frac{dx}{x}<br />
...I'm not sure I remember that


    thanks,
    db
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor

    Joined
    Apr 2005
    Posts
    14,973
    Thanks
    1121
    You cancel the two "x"s. You learned that in the third grade.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Simplification 2
    Posted in the Algebra Forum
    Replies: 6
    Last Post: April 25th 2011, 06:06 AM
  2. Simplification :)
    Posted in the Algebra Forum
    Replies: 9
    Last Post: April 24th 2011, 07:20 PM
  3. Replies: 1
    Last Post: December 15th 2009, 07:26 AM
  4. simplification
    Posted in the Algebra Forum
    Replies: 4
    Last Post: December 2nd 2009, 07:53 AM
  5. Simplification
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: February 28th 2008, 06:42 PM

Search Tags


/mathhelpforum @mathhelpforum