Results 1 to 6 of 6

Math Help - Critical numbers and open intervals

  1. #1
    Newbie
    Joined
    Nov 2011
    Posts
    3

    Critical numbers and open intervals

    I'm stuck on a calculus problem on a practice exam! So if anyone could help me out that would be fantastic!

    The equation is y= x^3 + x^2 - 6X
    asdfasdjfasdfadfasda3assjjjdff2

    Find all critical numbers and open intervals (increasing and decreasing)

    thanks!!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,236
    Thanks
    29

    Re: Critical numbers and open intervals

    Solve \frac{dy}{dx}=0
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Nov 2011
    Posts
    3

    Re: Critical numbers and open intervals

    I guess I dont understand...do you use chain rule? which confuses me as well
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,236
    Thanks
    29

    Re: Critical numbers and open intervals

    You won't need the chain rule here.

    Consider the rule if y= x^n \implies \frac{dy}{dx}= nx^{n-1}

    If your equation is y= \frac{x^3}{3}+\frac{x^2}{2}-6x use the rule term by term.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Nov 2011
    Posts
    3

    Re: Critical numbers and open intervals

    So would the correct answer be y'= 3x^2 + 2x - 6?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,236
    Thanks
    29

    Re: Critical numbers and open intervals

    It would be y' = x^2 + x - 6 now solve for y'=0
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. open/closed intervals
    Posted in the Discrete Math Forum
    Replies: 5
    Last Post: December 7th 2011, 09:38 AM
  2. max min on open closed intervals
    Posted in the Calculus Forum
    Replies: 4
    Last Post: December 10th 2010, 04:16 AM
  3. Open Intervals
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 14th 2009, 08:13 PM
  4. Open Intervals
    Posted in the Calculus Forum
    Replies: 2
    Last Post: October 24th 2009, 02:05 AM
  5. Covering rational numbers by countable open intervals
    Posted in the Differential Geometry Forum
    Replies: 3
    Last Post: September 26th 2009, 07:44 PM

Search Tags


/mathhelpforum @mathhelpforum