MHB Implicit differentiation difficult

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The discussion focuses on finding the second derivative y'' in terms of x and y, given the first derivative y' = tan(y) / (1 - x sec^2(y)). One participant expresses frustration that their answer does not match the results from Wolfram Alpha, despite checking their work multiple times. Another contributor provides the formula for y'' and emphasizes the importance of using the chain rule and simplifying the expression. The conversation highlights the challenges of implicit differentiation, particularly in managing algebraic complexity. Participants seek clarity and verification of their calculations to ensure accuracy.
Fermat1
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Given that $y'=\frac{tan(y)}{1-xsec^2(y)}$, find y'' in terms of $x$ and $y$ only.

I've done this and checked my work several times but my answer does not agree with wolfram alpha. Sorry for not posting my work, I am a bit busy at the moment. Can someone show the first couple of lines of work to see if it agrees with mine?

Thanks
 
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Fermat said:
Given that $y'=\frac{tan(y)}{1-xsec^2(y)}$, find y'' in terms of $x$ and $y$ only.

I've done this and checked my work several times but my answer does not agree with wolfram alpha. Sorry for not posting my work, I am a bit busy at the moment. Can someone show the first couple of lines of work to see if it agrees with mine?

Thanks
It's straight-forward Calculus, lots of good chain rule exercise, but somewhat appalling in the Algebra.

[math]y'' = \frac{sec^2(y) y' (1 - x~sec^2(y)) - tan(y) (-sec^2(y) - x(2) sec(y) sec(y)~tan(y) y')}{(1 - x~sec^2(y))^2}[/math]

Plug in your value for y' and simplify.

-Dan
 
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There are probably loads of proofs of this online, but I do not want to cheat. Here is my attempt: Convexity says that $$f(\lambda a + (1-\lambda)b) \leq \lambda f(a) + (1-\lambda) f(b)$$ $$f(b + \lambda(a-b)) \leq f(b) + \lambda (f(a) - f(b))$$ We know from the intermediate value theorem that there exists a ##c \in (b,a)## such that $$\frac{f(a) - f(b)}{a-b} = f'(c).$$ Hence $$f(b + \lambda(a-b)) \leq f(b) + \lambda (a - b) f'(c))$$ $$\frac{f(b + \lambda(a-b)) - f(b)}{\lambda(a-b)}...

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