Quotient Rule Proof

In this video, I show you how to proof the Quo Chen Lu formula (aka Quotient Rule) from the Prada Lu and the Chen Lu (aka Product Rule and the Chain Rule).

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blackpenredpen | 曹老師

[drpeyam]

Beautiful Intro! 🥰 And of course: Chen Lu!!! 😄

[hisxmark]

I don't think it matters how many languages you can speak if you can speak mathematics.

[artursanti]

We also have to deal with books not using factoreo wtf

[mrjnutube]

As usual, such a nice video, well explained and easy to understand. Well done. Thanks

[robertketcham]

Wow! My professor went totally off the deep end with his explanation. Used some version of the trigonometric half angles…in short, he confused everybody in class, and then told us that we would have to memorize it for the test. I am going to submit the method you used tomorrow in class and ask if it would be acceptable. Thank you so much!!!

[beatoriche]

I never really considered the quo chen lu to be its own rule, namely because it can very easily be derived from the prada lu and the chen lu. Sure, you could derive all the other rules using just the chen lu and the derivative of e^x, but the prada lu and the power rule come up frequently enough. However, the quo chen lu doesn’t really come up in a lot of contexts where it isn’t just as convenient to use the prada lu instead. To me, it just seems like an unnecessary formula to memorize – but maybe that’s just because my way of learning is weird. If I may ask, what are the experiences of your students with the quo chen lu? Does learning it facilitate their journey through calculus?

[-]

The way this was taught to me was using this:

Low d high plus high d low, draw a line and square below

[ericventalon]

C est vraiment super ces vidéos. Vous avez une très bonne pédagogie, de l humour. Vous êtes tous les deux géniaux !. 👍👍

[anshumaningale]

VERY WELL AND PREECISE EXPLANATION THANK YOU VEERY VEERY MUCH

[smokescreen]

But....



But it's *Koshen Lu*

[joelwilcox]

For the past several years, I’ve been stuck on this one math puzzle:

Imagine with a circle, with radius R, and draw a circular sector with an angle theta. Next, draw a chord, thus creating a triangle, and a circular segment. What angle does theta need to be so that the triangle and circular segment are equal in area?

I cheated a bit, so I already know the angle is (approximately) 1.895~ radians. I’m not, to be completely honest, interested in the value of theta; I’m interested, instead, in an expression that defines theta exactly (kinda like how Pi can be expressed as an infinite sum.)

[patrickammons]

blackpenredpen can you do a video on integrating this formula to get a Quo Chen Lu version of Integration by Parts? My friend and I figured it out but I wanted to know if it had any uses.

[aurithrabarua]

Finally it has come on my birthday!!! 😁😁😁😁

[janouglaeser]

The chain rule is unnecessary here:
One begins wih the product rule, (hg)' = h'g + hg'
(hg)' - hg' = h'g
[(hg)' - hg']/g = h'
[g(hg)' - hgg']/g² = h'
Now, let h=f/g (therefore hg = f). By replacing we get:
[gf' - fg']/g² = (f/g)'. There we have it.

[dr.rahulgupta]

Sir We can also have : g = e^ (ln g ), f= e^(ln f) then f/g = e^ (lnf -- lng ) then we can proceed to differentiate as usual to get ( f/g ) ' = e^ (lnf -- lng ) . ( f' / f -- g' / g = f/g ( f' /f -- g' / g ) = (gf' -- fg' )/ g^2

[hjk]

Could you do a video showing how to prove the 2πr circumference formula by taking the limit as n approaches infinity of the perimeter of an n-sided polygon inscribed in a circle? That would be awesome! 😀

[vijaynath]

Disclaimer ploddud dule means product rule and davvededd rule means division rule 😁😁😁😁

[imbreakingdown]

I literally googled who tf is Quo Chen Lu😒

[blackholesun]

2:20 d/DX(1/y) = (dy/DX) * (d(1/y) /dy )

[calm.aware.]

Next time use 律 instead of „Lu“ 😉
(Yes, I know the pronunciation differs slightly but at least it means „rule“.)