Implicit Differentiation Example: Folium of Descartes + Math History

avatar
(Edited)

In this video I go over another example on implicit differentiation and now look at the famous cubic function, the Folium of Descartes. I also go over some very interesting historical facts in the history of math so make sure you watch this video!


Watch video on:

Download video notes: https://1drv.ms/b/s!As32ynv0LoaIiJkYwUeXAOyrZSsvWA?e=VphTtX


View Video Notes Below!


Download these notes: Link is in video description.
View these notes as an article: https://peakd.com/@mes
Subscribe via email: http://mes.fm/subscribe
Donate! :) https://mes.fm/donate

Reuse of my videos:

  • Feel free to make use of / re-upload / monetize my videos as long as you provide a link to the original video.

Fight back against censorship:

  • Bookmark sites/channels/accounts and check periodically
  • Remember to always archive website pages in case they get deleted/changed.

Join my private Discord chat room: https://mes.fm/chatroom

Check out my Reddit and Voat math forums:

Buy "Where Did The Towers Go?" by Dr. Judy Wood: https://mes.fm/judywoodbook
Follow along my epic video series:


NOTE #1: If you don't have time to watch this whole video:

NOTE #2: If video volume is too low at any part of the video:


Implicit Differentiation: Example on the Folium of Descartes

Implicit Differentiation Example Descartes.jpeg

Folium of Descartes

x3 + y3 = 3axy

First proposed by the French mathematician René Descartes in 1638.

Its claim to fame lies in an incident in the development of calculus. Descartes challenged Pierre de Fermat to find the tangent line to the curve at an arbitrary point since Fermat had recently discovered a method for finding tangent lines. Fermat solved the problem easily, something Descartes was unable to do. Since the invention of calculus, the slope of the tangent line can be found easily using implicit differentiation. - Wikipedia

Example

If a = 2

(a) Find y’

(b) Find equation of tangent line at the point (3, 3)

(c) At what points on the curve is the tangent line horizontal?

Solution

image.png

image.png

image.png

image.png

image.png

image.png

Explicit Solution of the Folium

Implicit Differentiation makes finding derivatives very easy without solving explicitly for f(x).

There is a formula similar to the Quadratic Formula but for Cubic Functions (but much more complex). We can solve for the 3 functions of the Folium of Descartes:

image.png

image.png

Interesting Historical Facts

The Norwegian mathematician Niels Abel proved in 1824 that no general formula can be given for the roots of a fifth-degree equation in terms of radicals (i.e. square roots, cube roots, etc.).

Later the French mathematician Evariste Galois proved that it is impossible to find a general formula for the roots of an n-th degree equation (in terms of algebraic operations on the coefficients) if n is any integer larger than 4.

Moreover, implicit differentiation works just as easily for equations such as:

y5 + 3x2y2 + 5x4 =12

for which it is impossible to find a similar expression for y in terms of x.



0
0
0.000
0 comments