Results 1 to 2 of 2

Math Help - differentiate the following:

  1. #1
    Junior Member
    Joined
    Apr 2011
    Posts
    29

    differentiate the following:

    hello, I am hoping someone can help me understand a step.

    Q1.

    y = In [ (x+2) /
    sqrt (x-1)]

    y = In (x+2) - 1/2 In (x-1)

    dy/ dx = 1/x+2 - 1/2 (1/x-1)

    Now I don't understand where, on top, x-4. How do you get that??

    Answer is dy/dx = x-4 / 2(x+2)(x-1)

    Another example.

    Q2.
    y = In [ (x+1) /
    sqrt (x-1)]

    answer is = x-3 / 2(x^2 -1) . how come?

    Many thanks in advance!!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Banned
    Joined
    Oct 2009
    Posts
    4,261
    Quote Originally Posted by Jon123 View Post
    hello, I am hoping someone can help me understand a step.

    Q1.

    y = In [ (x+2) /
    sqrt (x-1)]

    y = In (x+2) - 1/2 In (x-1)

    dy/ dx = 1/x+2 - 1/2 (1/x-1)

    Now I don't understand where, on top, x-4. How do you get that??

    Answer is dy/dx = x-4 / 2(x+2)(x-1)


    What about common denominator??

    \frac{1}{x+2}-\frac{1}{2(x-1)}=\frac{2(x-1)-(x+2)}{2(x-1)(x-2)}=\frac{x-4}{2(x-1)(x+2)}



    Another example.

    Q2.
    y = In [ (x+1) /
    sqrt (x-1)]

    answer is = x-3 / 2(x^2 -1) . how come?


    Same thing as above. This is basic algebra...

    Tonio



    Many thanks in advance!!
    .
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. differentiate tan^3[2x]
    Posted in the Calculus Forum
    Replies: 1
    Last Post: September 15th 2010, 04:07 AM
  2. Differentiate 1 / (t+3e^t)
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: July 11th 2010, 10:40 PM
  3. differentiate
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: March 9th 2009, 11:22 AM
  4. How do you differentiate e^xy?
    Posted in the Calculus Forum
    Replies: 3
    Last Post: February 28th 2009, 08:57 AM
  5. differentiate y=a(1-exp^-bx)
    Posted in the Calculus Forum
    Replies: 1
    Last Post: October 10th 2008, 03:09 AM

Search Tags


/mathhelpforum @mathhelpforum