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Thread: In desperate need of Math Help!!!! +rep

  1. #1

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    In desperate need of Math Help!!!! +rep

    i have a few questions that are really pissing me off. if anyone could walk me through them i would greatly appreciate it.

    also i will +rep anyone who can help.




    Find the Vertex of the function (put the function in vertex for first): f(x)=8+2x-x^2
    [9/3/12 11:11:58 PM] Joanna: sigh
    [9/3/12 11:12:14 PM] Joanna: john
    [9/3/12 11:12:16 PM] Joanna: is
    [9/3/12 11:12:17 PM] Joanna: perfect

  2. #2
    Ray-Chill's Avatar
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    =] Awesome! We just learned about this.
    xD
    Firstly, put your equation into the format ax^2+bx+c=0. I'm assuming you know the quadratic formula to find the x intercepts,
    x = (-b +or- SQRT(b^2-4ac))/2a

    The vertex will lie on the axis of symmetry of the parabola, which is halfway between the x-intercepts ie -b/2a. Use that to work out x, and then substitute it back into the quadratic to find the y value.

    Eg1. y=-x^2+2x+8 here a=-1, b=2 and c=8
    So -b/2a = -2/2(-1)
    = 1
    Then substitute x=1 into the quadratic
    y=-1+2+8
    =9
    Therefore the vertex is (1, 9)
    ~ <3 ~ <3 ~ <3 ~ <3 ~


    “Of course it hurts, it’s a spanking. How else would it work?”


  3. #3
    Victoria's Avatar
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    its (-1.-9) according to this



    Infamous Joe is you.

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    MasterMind0wnz's Avatar
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    I have something that will help you greatly if you don't already know it. PM Me.

  5. #5

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    ack is it negative or positive?
    [9/3/12 11:11:58 PM] Joanna: sigh
    [9/3/12 11:12:14 PM] Joanna: john
    [9/3/12 11:12:16 PM] Joanna: is
    [9/3/12 11:12:17 PM] Joanna: perfect

  6. #6
    zlolekim's Avatar
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    Its positive John

  7. #7
    MasterMind0wnz's Avatar
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    Vertex: (1,9)

  8. #8
    Victoria's Avatar
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    sorry for giving you the wrong answer ^_^ i just googled it seemed legit!



    Infamous Joe is you.

  9. #9

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    thanks guys! repping everyone who helped
    [9/3/12 11:11:58 PM] Joanna: sigh
    [9/3/12 11:12:14 PM] Joanna: john
    [9/3/12 11:12:16 PM] Joanna: is
    [9/3/12 11:12:17 PM] Joanna: perfect

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