Results 1 to 3 of 3

Math Help - simple differention problem

  1. #1
    Senior Member furor celtica's Avatar
    Joined
    May 2009
    Posts
    271

    simple differention problem

    Use the substitution u= 2(x^2) + 3 to differentiate y= 1/(sqrt(2(x^2) + 3))

    Alright so Iím pretty sure I got this right:
    y= f(u)= 1/sqrt(u) = (u)^(-1/2)
    => dy/du = (-1/2)(u^(-3/2))= (-1/2)((2(x^2) + 3)^(-3/2))
    du/dx= 4x

    so dy/dx = (dy/du) x (du/dx) = -2x/(sqrt((2(x^2) + 3)^3)

    However, the given answer is 2/(sqrt((2(x^2) + 3)^3)
    Is this a typo?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Nov 2011
    From
    Crna Gora
    Posts
    420
    Thanks
    64

    Re: simple differention problem

    Maple 14 says that your answer is correct...
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member sbhatnagar's Avatar
    Joined
    Sep 2011
    From
    New Delhi, India
    Posts
    200
    Thanks
    17

    Re: simple differention problem

    Your answer and working are totally correct. There are two possibilities now:

    1)There's a typo in your book. .........<---This seems most probable to me.
    or
    2)You have solved the wrong question.

    Any way you can check your answer here at this website: wolfram alpha
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Differention help
    Posted in the Calculus Forum
    Replies: 4
    Last Post: March 23rd 2011, 03:04 AM
  2. differention (equation of tangent)
    Posted in the Calculus Forum
    Replies: 5
    Last Post: February 25th 2010, 03:48 AM
  3. Implicit Differention
    Posted in the Calculus Forum
    Replies: 2
    Last Post: July 10th 2009, 04:50 PM
  4. differention 2
    Posted in the Calculus Forum
    Replies: 6
    Last Post: September 5th 2008, 08:08 PM
  5. Help with logarithmic differention
    Posted in the Calculus Forum
    Replies: 2
    Last Post: January 24th 2008, 03:05 PM

Search Tags


/mathhelpforum @mathhelpforum