Results 1 to 4 of 4

Math Help - chain rule again

  1. #1
    Member
    Joined
    Jan 2008
    Posts
    91

    chain rule again

    hey there..just studying for the exam,,im pretty sure im correct but i just wanted to make sure....

    differentiate --- (sqrt(x^3+5))

    by using the chain rule i get my answer to be....

    (1/2(x^3+5)^(-1/2)) . 3x^2

    the answer says.....

    3x^2 / 2sqrt(x^3+5)


    Are they the same??? my answer and the proper answer?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,889
    Thanks
    326
    Awards
    1
    Quote Originally Posted by b00yeah05 View Post
    hey there..just studying for the exam,,im pretty sure im correct but i just wanted to make sure....

    differentiate --- (sqrt(x^3+5))

    by using the chain rule i get my answer to be....

    (1/2(x^3+5)^(-1/2)) . 3x^2

    the answer says.....

    3x^2 / 2sqrt(x^3+5)


    Are they the same??? my answer and the proper answer?
    They are the same.
    \frac{1}{\sqrt{x}} = x^{-1/2}

    -Dan
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,707
    Thanks
    627
    Hello, b00yeah05!

    You need to polish up your algebra . . .


    Differentiate: . f(x)\:=\:\sqrt{x^3+5}

    By using the chain rule i get my answer to be: . f'(x) \:=\:\frac{1}{2}(x^3+5)^{-\frac{1}{2}}\cdot 3x^2

    The answer says: . \frac{3x^2}{2\sqrt{x^3+5}}

    Are they the same? . . . . . You really can't tell?

    Your answer is: . \frac{1}{2}(x^3+5)^{-\frac{1}{2}}\cdot3x^2 \;=\;\frac{1}{2}\cdot\frac{1}{(x^3+5)^{\frac{1}{2}  }}\cdot 3x^2 \;= \;\frac{3x^2}{2(x^3+5)^{\frac{1}{2}}} \;=\;\frac{3x^2}{2\sqrt{x^3+5}}

    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Jan 2008
    Posts
    91
    no i really cant, i really get confused with powers...its not my thing...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 9
    Last Post: November 9th 2010, 01:40 AM
  2. Chain Rule Inside of Chain Rule
    Posted in the Calculus Forum
    Replies: 3
    Last Post: October 22nd 2009, 08:50 PM
  3. Replies: 5
    Last Post: October 19th 2009, 01:04 PM
  4. Replies: 3
    Last Post: May 25th 2009, 06:15 AM
  5. Replies: 2
    Last Post: December 13th 2007, 05:14 AM

Search Tags


/mathhelpforum @mathhelpforum