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Math Help - Analyzing a graph

  1. #1
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    Analyzing a graph

    I need to find the X-intercepts of:

    Y= 3x^4 - 6x^2 + 5/3

    Thank you for any help.
    I have been away from any math for over five years so a step by step would be appreciated.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by JDG1317 View Post
    I need to find the X-intercepts of:

    Y= 3x^4 - 6x^2 + 5/3

    Thank you for any help.
    I have been away from any math for over five years so a step by step would be appreciated.
    the x-intercepts occur where y = 0. note that this function is quadratic in x^2. if you say, let k = x^2 for instance, the result is:

    y = 3k^2 - 6k + 5/3

    can you solve that for y = 0
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  3. #3
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    I really don't even know what to do from there. Sorry for being a pain. I really should have relearned some of these skills before signing up for calc class.
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by JDG1317 View Post
    I really don't even know what to do from there. Sorry for being a pain. I really should have relearned some of these skills before signing up for calc class.
    use the quadratic formula.

    for a quadratic of the form y = ax^2 + bx + c the roots (that is, the solution(s) to ax^2 + bx + c = 0) are given by:

    x = \frac {-b \pm \sqrt{b^2 - 4ac}}{2a}

    use that to solve for k. when done, replace k with x^2 and solve for x
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  5. #5
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    When I used the quadratic equation I got:

    k= 3 and,
    k= .6

    When I replaced k with X^2 I get

    X= +/- sqrt(3)
    X= +/- sqrt(.6)

    These answers don't match up with the intercepts when I check them on the graphing calc.
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  6. #6
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by JDG1317 View Post
    When I used the quadratic equation I got:

    k= 3 and,
    k= .6

    When I replaced k with X^2 I get

    X= +/- sqrt(3)
    X= +/- sqrt(.6)

    These answers don't match up with the intercepts when I check them on the graphing calc.
    of course they don't match up. those answers are wrong. those are not the values for k
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