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    Stuck on question 7. I've differentiated it, made it equal to zero,but no clue how to find the coordinates.

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    For dy /dx I got -4x-y /x +2y I don't understand how to get two values making it zero unless I got the equation wrong.
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    (Original post by eggfriedrice)
    Stuck on question 7. I've differentiated it, made it equal to zero,but no clue how to find the coordinates.

    Name:  Screenshot_2013-04-04-22-18-41.png
Views: 71
Size:  244.9 KB

    For dy /dx I got -4x-y /x +2y I don't understand how to get two values making it zero unless I got the equation wrong.
    Substitute into the equation of the curve

    There are infinitely many solutions to y=-4x, but you have 2 constraints on x and y.
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    use the fact that the numerator has to be equal to zero (not the denom) - solve for y=, then put back into the implicit equation, solve for x, then put each value of x back into the equation numerator, solve for y=
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    Thanks! Got it.
 
 
 
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