Derive using Taylor series/Establish error term

trouty323
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Homework Statement



Derive the following formula using Taylor series and then establish the error terms for each.

Homework Equations



f ' (x) ≈ (1/2*h) [4*f(x + h) - 3*f(x) - f(x+2h)]

The Attempt at a Solution



I honestly have no idea how to go about deriving this. The professor did not require a book for this class, and he never did an example. Any help would be greatly appreciated.
 
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trouty323 said:

Homework Statement



Derive the following formula using Taylor series and then establish the error terms for each.

Homework Equations



f ' (x) ≈ (1/2*h) [4*f(x + h) - 3*f(x) - f(x+2h)]

The Attempt at a Solution



I honestly have no idea how to go about deriving this. The professor did not require a book for this class, and he never did an example. Any help would be greatly appreciated.

Do you know what a Taylor series is? If so, apply it to f(x+h) and f(x+2h), keeping just a few terms in each expansion.

RGV
 
Ray Vickson said:
Do you know what a Taylor series is? If so, apply it to f(x+h) and f(x+2h), keeping just a few terms in each expansion.

RGV

Honestly, it's been several years since I've worked with Taylor series. The class is Numeral Methods. I'm confused by how the formula is set up. Everything I've looked up online does not look like this at all.
 
Anybody?
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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