Results 1 to 4 of 4

Math Help - [SOLVED] quotient rule.

  1. #1
    Member
    Joined
    Jul 2009
    Posts
    149

    [SOLVED] quotient rule.

    f(x)=\frac{10x+3}{5x^2+3x-6}

    f(x)=\frac{[(10)(5x^2+3x-6)]-[10x+3)(10x+3]}{(5x^2+3x-6)}

    f(x)=\frac{(50x^2+30x-60)-(10x+3)^2}{(5x^2+3x-6)^2}

    f(x)=\frac{(50x^2+30x-60)-(10x^2+9)}{(5x^2+3x-6)^2}

    f'(x)= \frac{40x^2+30x-69}{(5x^2+3x-6)^2}

    Did i do that right or is the end part
     \frac{40x^2+30x-51}{(5x^2+3x-6)^2}

    ????
    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 el123 View Post
    f(x)=\frac{10x+3}{5x^2+3x-6}

    f(x)=\frac{[(10)(5x^2+3x-6)]-[10x+3)(10x+3]}{(5x^2+3x-6)}

    f(x)=\frac{(50x^2+30x-60)-(10x+3)^2}{(5x^2+3x-6)^2}

    f(x)=\frac{(50x^2+30x-60)-(10x^2+9)}{(5x^2+3x-6)^2}

    f'(x)= \frac{40x^2+30x-69}{(5x^2+3x-6)^2}

    Did i do that right or is the end part
     \frac{40x^2+30x-51}{(5x^2+3x-6)^2}

    ????
    Check your answer here: Wolfram|Alpha (click Show Steps).
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member Matt Westwood's Avatar
    Joined
    Jul 2008
    From
    Reading, UK
    Posts
    822
    Thanks
    31
    On the fourth line you seem to have gone from (10x + 3)^2 to 10x^2 + 9 which is mentioned here:

    Freshman's Dream - ProofWiki

    as it's such a popular mistake to make.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Jul 2009
    Posts
    149
    Thats was all a bit confusing there for a while, but i have figured it out.

    Thanks for both those sites! Im sure they will come in handy.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 5
    Last Post: December 20th 2011, 04:57 AM
  2. [SOLVED] Can't solve this with quotient rule!!
    Posted in the Calculus Forum
    Replies: 4
    Last Post: April 9th 2010, 10:09 PM
  3. [SOLVED] quotient rule on holomorphic functions
    Posted in the Differential Geometry Forum
    Replies: 3
    Last Post: February 9th 2010, 11:45 AM
  4. [SOLVED] Derivative Quotient Rule
    Posted in the Calculus Forum
    Replies: 7
    Last Post: October 20th 2009, 03:09 PM
  5. [SOLVED] Dirivative Help [Quotient Rule]
    Posted in the Calculus Forum
    Replies: 1
    Last Post: December 18th 2007, 12:01 PM

Search Tags


/mathhelpforum @mathhelpforum