Results 1 to 10 of 10

Math Help - #5) Find the x-value of all pints where the function has relative extrema...

  1. #1
    Member
    Joined
    Jan 2008
    Posts
    78

    #5) Find the x-value of all pints where the function has relative extrema...

    Find the x-value of all points where the function has relative extrema. Find the values of any relative extrema.

    f(x)=x^3-12x+2
    y'=3x^2-12=0
    y'=3x^2=12
    y'=x^2=4

    Now after this point what i did was take the square root of each side. Now aren't i supposed to end up with +/- 2 and find the matching y-values? I get:
    Max:0@-2
    Min:0@2
    But the computer say this is wrong i know that 0@2 is right but where did i go wrong?
    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 plstevens View Post
    Find the x-value of all points where the function has relative extrema. Find the values of any relative extrema.

    f(x)=x^3-12x+2
    y'=3x^2-12=0
    y'=3x^2=12
    y'=x^2=4

    Now after this point what i did was take the square root of each side. Now aren't i supposed to end up with +/- 2 and find the matching y-values? I get:
    Max:0@-2
    Min:0@2
    Mr F says: I have no idea what the above notation is meant to mean.

    But the computer say this is wrong i know that 0@2 is right but where did i go wrong?
    Stationary points at x = 2 or x = -2.

    Minimum turning point at x = 2 and maximum turning point at x = -2.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jan 2008
    Posts
    78
    min and max are for the relative maximum, and the relative minimum
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by plstevens View Post
    min and max are for the relative maximum, and the relative minimum
    I am aware of that. I was referring to the 0@-2 and 0@2 business. Try to use standard mathematical notation if you want people to make sense of what you post.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Jan 2008
    Posts
    78
    well that's how my teacher posted it, i was very unaware that this was incorrect, sorry if i confused you, but are you able to help
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Jan 2008
    Posts
    78
    it just means 0 at 2, 0 being y and 2 being x
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by plstevens View Post
    well that's how my teacher posted it, i was very unaware that this was incorrect, sorry if i confused you, but are you able to help
    See reply #2.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Member
    Joined
    Jan 2008
    Posts
    78
    i think its relative minimum of 0 at 2, thats how it is in the anwer choice
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by plstevens View Post
    i think its relative minimum of 0 at 2, thats how it is in the anwer choice
    f(2) = 2^3 - 12(2) + 2 \neq 0. The minimum value at x = 2 is NOT 0.
    Follow Math Help Forum on Facebook and Google+

  10. #10
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,393
    Thanks
    1327
    The problem, as you posted it, was "Find the x-value of all points where the function has relative extrema". Those x values are -2 and 2. The problem did not ask for the corresponding y values.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: January 18th 2011, 06:35 AM
  2. Replies: 1
    Last Post: June 2nd 2010, 09:45 AM
  3. Find relative extrema
    Posted in the Calculus Forum
    Replies: 3
    Last Post: November 10th 2009, 11:13 PM
  4. find the relative extrema of the function
    Posted in the Calculus Forum
    Replies: 0
    Last Post: November 9th 2008, 10:04 AM
  5. find the value of any relative extrema.
    Posted in the Calculus Forum
    Replies: 1
    Last Post: September 24th 2008, 03:19 PM

Search Tags


/mathhelpforum @mathhelpforum