Differentiation in history, Pierre de Fermat and René Descartes.

NinjaKiwi

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Differentiation in history, Pierre de Fermat and René Descartes.

Hello.
Can anyone help me find the tangent of sqrt(ax) (a is a positive real number), using the methods of Pierre de Fermat and René Descartes and also with the method of today?
 
Thank you, but I've seen that tread.
It's just that the "a" confuses me, I have no idea where to put it in the equation.
 
Then what is required is a general formula for the tangent of \(\displaystyle \sqrt{ax}\) at some point.

Per the reference, we can let \(\displaystyle y=\sqrt{ax}\).

This gives \(\displaystyle x^{2}+(a-2c)x+2c-2=0\)

The discriminant must be 0:

\(\displaystyle (a-2c)^{2}-4(1)(2c-2)=0\)

Solving for c gives \(\displaystyle c=\frac{\pm 2\sqrt{a-1}+a+2}{2}\)
 
Thank you!

One question though, does it matter if I use (a-x)^2 instead of (a-y)^2 in the circle equation?
Do the results differ?
 
Thank you!

One question though, does it matter if I use (a-x)^2 instead of (a-y)^2 in the circle equation?
Do the results differ?

That'll depend on your problem -

which way the center of the circle is shifted (relative to the origin)?
 
And can anyone tell me, if the derivative of f(x)=sqrt(ax) is f'(x)=a/(2sqrt(ax))
 
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