Understanding the Maclaurin Series

integrationtaylor expansion

So I have been using the following link to try to understand the Maclaurin Series: Link. I was given an explanation in class, but it didn't explain things enough, so I have tried Khan Academy.

I understand that a Maclaurin series is approximating another function using a polynomial. However, I don't understand the form that is used in both the Khan Academy video, and the explanation my teacher gave me:

The first one is what I learned in class, and the second one is what I learned from the Khan Academy video

So the definition with the a terms is what I learned from my math class, and the one with the f(0) terms is from the Khan academy video.

So focusing on the second one, I have a few questions:
Why do the factors and x powers correspond to integrating? For instance, if you look at the third term with x^2 and 1/2, then look at the second term, which multiples by 1/3, it seems like the process of integrating (or anti differentiating, whichever you prefer). Why is that?

Also, is there some intuitive explanation for why we use derivatives in the first place? Why does that, of all things, help us approximate or mimic a function?

I appreciate any help, as I am still grappling with this topic.
Thanks!

Best Answer

There is an excellent YouTuber named 3Blue1Brown who you may have seen on advertisements in this very site. His goal is for "explanations to be driven by animations and for difficult problems to be made simple with changes in perspective."

Here you can find the video he made on the Taylor Series Expansion. I am also learning it right now and it is actually very helpful. Try to check his other videos to intuitively understand the quaternions, the Basel problem, eigenvectors and eigenvalues, etc.

Note: This is by no means a paid advertisement, I am simply a huge fan and he has helped a lot of people understand and love mathematics, including me.

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