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Math Help - solving equation

  1. #1
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    solving equation

    The graphs with equations and meet at two points. At one of these points, . What is the value of at the other point?

    I dont know how to do this question, I think i should set them equal to each other,

    any help appreciated.
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: solving equation

    I recommend substituting for y as given by the first equation into the second equation. This will given you a quadratic in x. Solve this, then plug the root not equal to 2 into the first equation for x to determine the value of y at the other point.
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  3. #3
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    Re: solving equation

    Quote Originally Posted by MarkFL2 View Post
    I recommend substituting for y as given by the first equation into the second equation. This will given you a quadratic in x. Solve this, then plug the root not equal to 2 into the first equation for x to determine the value of y at the other point.

    Am a bit confused, i did what you said

     9x^{2} - 4 = 1

    9x^{2} -20 = 0 [/tex]




    and got  x = \frac{2\sqrt{5}}{3}

    so i plug this answer into the first equation to get an answer for y ?
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  4. #4
    MHF Contributor MarkFL's Avatar
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    Re: solving equation

    If you substitute for y using the first equation, into the second equation, you get:

    x\left(\frac{9}{4}x-4 \right)=1

    Distribute the x on the left side:

    \frac{9}{4}x^2-4x=1

    Multiply through by 4:

    9x^2-16x=4

    Write quadratic in standard form:

    9x^2-16x-4=0

    Now factor to find the roots.
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