Results 1 to 4 of 4

Math Help - Horizontal tangents and Finding Derivative

  1. #1
    Member
    Joined
    Oct 2007
    Posts
    178

    Horizontal tangents and Finding Derivative

    Find the horizontal tangents of the curve:
    y= x^4 - 7x^3 + 2x^2 + 15

    The lesson is about shortcut rules for derivatives.
    Rules such as:
    Power rule- x^n = nx^(n-1)
    Power Rule of positive integer- same
    Power Rule of negative integers- same
    Product rule- derivative of (uv) = derivative of u + derivative of v
    Constant function rule - derivative of any integer is 0
    Quotient rule- don't know how to LaTex or describe. Don't need for this though.


    I simplified the function to x(4x^2 - 21x +4) = 0 .
    I know the goal of horizontal tangents is to get 0 = 0

    Answers I got: x= 0
    There should be more, as that is the pattern of other problems.
    Is there any way to figure it out algebraically? I'm very bad at trial and error. I found nothing else.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Oct 2007
    Posts
    178

    find the derivative - support graphically

    Oops. Meant to make another thread. Oh well.
    Find dy/dx. Support your answer graphically.

    [tex](x^3 + x + 1)(x^4 + x^2 + 1)/MATH]

    Using derivative shortcuts again.

    Will paste them from other thread. ( see above)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor kalagota's Avatar
    Joined
    Oct 2007
    From
    Taguig City, Philippines
    Posts
    1,026
    Quote Originally Posted by Truthbetold View Post
    Find the horizontal tangents of the curve:
    y= x^4 - 7x^3 + 2x^2 + 15

    The lesson is about shortcut rules for derivatives.
    Rules such as:
    Power rule- x^n = nx^(n-1)
    Power Rule of positive integer- same
    Power Rule of negative integers- same
    Product rule- derivative of (uv) = derivative of u + derivative of v
    Constant function rule - derivative of any integer is 0
    Quotient rule- don't know how to LaTex or describe. Don't need for this though.


    I simplified the function to x(4x^2 - 21x +4) = 0 .
    I know the goal of horizontal tangents is to get 0 = 0

    Answers I got: x= 0
    There should be more, as that is the pattern of other problems.
    Is there any way to figure it out algebraically? I'm very bad at trial and error. I found nothing else.
    yes, you got the right one.. the other two are just try to solve using quadratic equation..
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor kalagota's Avatar
    Joined
    Oct 2007
    From
    Taguig City, Philippines
    Posts
    1,026
    Quote Originally Posted by Truthbetold View Post
    Oops. Meant to make another thread. Oh well.
    Find dy/dx. Support your answer graphically.

    [tex](x^3 + x + 1)(x^4 + x^2 + 1)/MATH]

    Using derivative shortcuts again.

    Will paste them from other thread. ( see above)
    use the shortcuts right?

    so, D_x((x^3 + x + 1)(x^4 + x^2 + 1)) = (x^3 + x +1)D_x(x^4 + x^2 + 1) + D_x(x^3 + x + 1) (x^4 + x^2 + 1)

    (x^3 + x +1)(4x^3 +2x) + (3x^2 +1)(x^4 + x^2 + 1)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: October 19th 2010, 03:51 AM
  2. Horizontal and Veritcal Tangents
    Posted in the Calculus Forum
    Replies: 0
    Last Post: October 19th 2009, 04:33 PM
  3. Horizontal Tangents
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 21st 2009, 09:46 PM
  4. x coordinates of horizontal tangents lines ?
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 20th 2008, 12:51 PM
  5. Horizontal and Vertical Tangents!
    Posted in the Calculus Forum
    Replies: 6
    Last Post: July 11th 2007, 08:20 AM

Search Tags


/mathhelpforum @mathhelpforum