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    Q14)

    I found dy/dx = (3y-3x^2)/(3y^2-3x)

    What do I from here?
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    Okay I equated dy/dx=0

    And got y=x^2
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    (Original post by Vorsah)
    Okay I equated dy/dx=0

    And got y=x^2
    See what happens when you substitute that equality into the original expression in terms of x and y.
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    (Original post by Khallil)
    See what happens when you substitute that equality into the original expression in terms of x and y.
    I get x=3^1/3
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    (Original post by Vorsah)
    I get x=3^1/3
    Try again.
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    (Original post by Khallil)
    Try again.
    Divided through by x^3
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    (Original post by Vorsah)
    Divided through by x^3
    First of all, you shouldn't be dividing by x^3 as you don't know if x could equal 0.

    Second of all, what's the value of x^3 - 3x^3 \ ?
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    (Original post by khallil)
    try again.
    x^3 + x^6 - 2x^3=0

    x^6 - 2x^3=0

    x^3(x^3 - 2)=0

    x=0
    x=2^1/3?
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    (Original post by Vorsah)
    x^3 + x^6 - 2x^3=0

    x^6 - 2x^3=0

    x^3(x^3 - 2)=0

    x=0
    x=2^1/3?
    My working concurs with yours. Now find their respective y coordinates.

    Do you know how to verify whether a point is a maximum, minimum or point of inflection?
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    (Original post by Khallil)
    My working concurs with yours. Now find their respective y coordinates.

    Do you know how to verify whether a point is a maximum, minimum or point of inflection?
    Yep
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    (Original post by Vorsah)
    Yep
    That's good to hear

    Out of interest, what are the answers at the back of the book for this question?
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    Max at 2^2/3
    Min at 0
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    (Original post by Khallil)
    That's good to hear

    Out of interest, what are the answers at the back of the book for this question?
    I got d^2y/dx^2 = -6x/(3y^2-3x)

    When sub in (2^1/3, 2^2/3) I get -2 = max, which is correct

    When I sub in (0,0) , I can't do it because you do 0/0, so how am I suppose find out?
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    (Original post by Vorsah)
    I got d^2y/dx^2 = -6x/(3y^2-3x)

    When sub in (2^1/3, 2^2/3) I get -2 = max, which is correct

    When I sub in (0,0) , I can't do it because you do 0/0, so how am I suppose find out?
    I also got 0/0 for my second derivative evaluated at the point (0, 0) and I'm unsure of how to resolve that.
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    Any1 else?
 
 
 
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