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-   -   Finding x-intercepts, local maximum, local minimum of graph (https://www.askmehelpdesk.com/showthread.php?t=68636)

  • Mar 4, 2007, 01:33 PM
    SpecialK
    Finding x-intercepts, local maximum, local minimum of graph
    How do I find the x-intercepts, local maximums, and local minimums of this graph -->
    f(x)=1/9(x-3)^2(x+3)^2

    using a graphing calculator?
  • Mar 4, 2007, 01:44 PM
    incognito
    For the x-intercepts, you would set Y to 0 and solve for x.
    And for max and min using a TI-83 Plus, when you're looking at your graph hit "2nd"-"Calc"(also the trace key). It is option 3 and 4 in that window for minimum and maximum.
    Hope that helps.
  • Apr 2, 2008, 06:38 PM
    Guest
    Finding a composite fuction and iits domain
  • Jan 22, 2009, 08:52 AM
    tomekdang
    How do I find the x-intercepts, local maximums, and local minimums of this graph -->
    f(x)=1/9(x-3)^2(x+3)^2
    We can find x-intercepts like that:
    f(x)=0 <=> 1/9(x-3)^2(x+3)^2 = 0 <=> x = 3 or x = -3
    one more thing, if you want to find the local maximum/minimum => you must do like that:
    f(x) = 1/9 (x-3)(x+3)(x-3)(x+3)
    <=> f(x) = 1/9 (x^2 - 9 )^2
    <=> f(x) = 1/9 [(x^2)^2 - 2.9.x^2 +9^2]
    <=> f(x) = 1/9 (x^4 -18x^2 +81)
    find f'(x)
    f'(x) = 1/9(4x^3 - 36x)
    find x when f'(x) = 0 <=> x = 0 or x = 3 or x = -3
    then find f''(x)
    f''(x) = 1/9(12x^2 - 36)
    determine local maximum and minimum:
    f''(0) = 1/9(12.0^2 -36) = -4 <0 => the local maximum of function at x = -4
    f''(3) = 1/9(12.3^2 -36) = 8 >0
    f''(-3)= 1/9[12.(-3)^2 - 36] = 8 >0
    => this function have 2 local minimum at x = -3 and x = 3
    can find y when you calculate x at f(x)
  • Sep 24, 2009, 07:10 PM
    tinabooe

    f(x)=0.2x^4+0.3x^3-0.8x^2+5
  • Sep 24, 2009, 11:05 PM
    morgaine300

    Can you please start your own thread for your question. I just looked through this whole thread just to find a different thing at the end. You also haven't asked a question.

    EDIT: Has been re-posted over here:
    https://www.askmehelpdesk.com/math-s...in-399632.html

    (That's why this is confusing.)

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