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Thread: Stuck on quadratic function past paper question

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    Question Stuck on quadratic function past paper question

    Hi, as the title suggests I am stuck on these two quadratic function question:

    The quadratic function is 3x^2-5x+2
    Solve
    a) 2alpha+3beta

    b) alpha^2beta^2

    Thanks
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    Re: Stuck on quadratic function past paper question

    a) idk if you typed this one correctly

    b) Square of the product of roots = (2/3)^2 = 4/9
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    Re: Stuck on quadratic function past paper question

    Well when you solve the equation you get the roots x=2/3 and x=1

    Then just let one of the roots be alpha and the other be beta. Then sub it into part a). I think part a) is a bit weird since you can't tell which root will be alpha and which will be beta since you are multiplying each one by a different number. If you typed part a) correctly, then you would have two different solutions.

    For b), just use the square of the product of roots formula (i.e. just multiply the square of 2/3 and 1 which gives 4/9)
    Last edited by captainhelium; 7 Sep 2017 at 1:38 PM.
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    Re: Stuck on quadratic function past paper question

    Oh, okay I thought you had to apply -b/a and c/a, that was pretty basic question then
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    Re: Stuck on quadratic function past paper question

    Yeah, it's pretty weird but it was in my schools past paper
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    Re: Stuck on quadratic function past paper question

    Quote Originally Posted by captainhelium View Post
    Well when you solve the equation you get the roots x=2/3 and x=1

    Then just let one of the roots be alpha and the other be beta. Then sub it into part a). I think part a) is a bit weird since you can't tell which root will be alpha and which will be beta since you are multiplying each one by a different number. If you typed part a) correctly, then you would have two different solutions.

    For b), just use the square of the product of roots formula (i.e. just multiply the square of 2/3 and 1 which gives 4/9)
    Yeah, it's pretty weird but it was in my school's past paper, I think they putted the question, to maybe prepare us for the HSC. :
    Last edited by highshill; 7 Sep 2017 at 5:19 PM.
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    Re: Stuck on quadratic function past paper question

    Quote Originally Posted by highshill View Post
    Yeah, it's pretty weird but it was in my school's past paper, I think they putted the question, to maybe prepare us for the HSC. :
    I'm pretty sure there's a typo in the question they're never gonna ask 2alpha + 3beta I bet they were meant to have 2alpha + 2beta or 3alpha + 3beta or something to apply -b/a
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    Re: Stuck on quadratic function past paper question

    Quote Originally Posted by pikachu975 View Post
    I'm pretty sure there's a typo in the question they're never gonna ask 2alpha + 3beta I bet they were meant to have 2alpha + 2beta or 3alpha + 3beta or something to apply -b/a
    I checked the question again it still say 2alpha+ 3beta, but I think you are right it Must be a typo, I'll ask my teacher tomorrow because our yearly are going on and tomorrow is mathematics, so it's urgent for me to ask them this question before it's too late.
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