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# Implicit differentiation- Alevel maths question watch

1. I have worked dy/dx=

(1-x^2)/y^2

and i know you set it equal to 0 but i’m confused on how to carry on? Any help appreciated
2. Turning points are maxima or minima. So yes, dy/dx=0 AND d2y/dx2 for those values should be positive or negative. Basically not 0
3. I think...
4. (Original post by InGodiTrust)
Turning points are maxima or minima. So yes, dy/dx=0 AND d2y/dx2 for those values should be positive or negative. Basically not 0
but how do I work them out
5. Your value of dy/dx as 0. Get solutions
6. Actually if you consider all stationary points to be turning points then you don’t need the d2y/dx2
7. (Original post by InGodiTrust)
Your value of dy/dx as 0. Get solutions
Yeah how?
8. I’m getting x as +/- 1. Plug that into the original to get your y values
9. Put (1-x2)/y2 as equal to 0
10. I started by saying that dy/dx will be zero when (x²-1)=0 and that gave me two values of x for two turning points.

Then subs these values back into the original eqn to find the corresponding y values.

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Updated: February 28, 2018
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