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Math Help - Finding the rational roots

  1. #1
    Junior Member
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    Finding the rational roots

    I'm kind of stuck on these problems and would appreciate some help.
    Also is there a way to find the rational roots on a Ti-84 graphing calculator?

    The problems that I have trouble with are...
    X^2-16=0
    X^3-15X+22=0
    X^4-7X^3+13X^2+X-20=0
    X^4+5X^3+3X^2+45X-54=0
    2X^4+X^3-22X^2+29X+20=0
    X^4-4X^3+7X^2-6X=0
    6X^3-31X^2+3X+10=0
    X^3-X^2-3X+2=0
    4X^3-8X^2+X+1=0

    Thank you in advance.
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  2. #2
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    Quote Originally Posted by Rainy2Day View Post
    I'm kind of stuck on these problems and would appreciate some help.
    Also is there a way to find the rational roots on a Ti-84 graphing calculator?

    The problems that I have trouble with are...
    X^2-16=0
    X^3-15X+22=0
    X^4-7X^3+13X^2+X-20=0
    X^4+5X^3+3X^2+45X-54=0
    2X^4+X^3-22X^2+29X+20=0
    X^4-4X^3+7X^2-6X=0
    6X^3-31X^2+3X+10=0
    X^3-X^2-3X+2=0
    4X^3-8X^2+X+1=0

    Thank you in advance.
    the first one x^2 - 16 is a difference of squares question
    if you are able to square root both terms AND they are being subtracted from one another you can write it like this

    x^2 - 16 = (x - 4)(x + 4), and x = 4, x = -4

    for the cubics (the ones that have 3rd degree or highest power is 3, ex the last in the list), check out this video

    Solving cubics

    you could use the calculator to graph the functions and then see if it tells you the X intercepts

    its probably easier to not use the calc though hehe
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  3. #3
    Junior Member
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    Thank you
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