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Math Help - Finding equation of curve

  1. #1
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    Finding equation of curve

    Could someone please help me with this question?
    Find the equation of curve COD, assuming it is of the form y = ax^2n
    points are C(-60,18) O(0,0), D(40,8)
    ive read some help for this question, but they mostly just say sub in the points and solve simultaneously
    ive tried this and i really need help with actually finding n and a, i have subbed in the points but i really dont no what do from there
    if anyone could help me with this question it would be much appreciated ! =D
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  2. #2
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    Quote Originally Posted by flyinhigh123 View Post
    Could someone please help me with this question?
    Find the equation of curve COD, assuming it is of the form y = ax^2n
    points are C(-60,18) O(0,0), D(40,8)
    ive read some help for this question, but they mostly just say sub in the points and solve simultaneously
    ive tried this and i really need help with actually finding n and a, i have subbed in the points but i really dont no what do from there
    if anyone could help me with this question it would be much appreciated ! =D
    Substitute (-60, 18): 18 = a (-60)^{2n} .... (1)

    Substitute (40, 8): 8 = a (40)^{2n} .... (2)

    Divide equation (1) by equation (2), simplify and solve for n. Use that value of n to substitute into one of the equations and solve for a.
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  3. #3
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    thanxx but im still having a little trouble =((

    i got
    18/8 = [(-60)^2n]/(40)^2n]
    cause the a cancels out

    and then i dont really no wat to do next
    how do i simplify that?
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  4. #4
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    Quote Originally Posted by flyinhigh123 View Post
    thanxx but im still having a little trouble =((

    i got
    18/8 = [(-60)^2n]/(40)^2n]
    cause the a cancels out

    and then i dont really no wat to do next
    how do i simplify that?
    \frac{9}{4} = \left( - \frac{60}{40} \right)^{2n}

    \Rightarrow \frac{9}{4} = \left( \left( - \frac{3}{2} \right)^{2}\right)^n

    \Rightarrow \frac{9}{4} = \left(\frac{9}{4}\right)^n

    \Rightarrow n = 1.
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