Taylor series expansion

In summary, to find the coefficient for the nth term of Tn(x) for sqrt[x] centered at a=1, you can use the Taylor series formula with a=1 and f(x) = sqrt[x], which results in the formula Tn(x) = sqrt[1] + 1/2(x-1) - 1/4(x-1)^2/2! + 3/8(x-1)^3/3! - 15/16(x-1)^4/4! + ... + (-1)^(n+1) * (2n-1)!! / 2^n * (x-1)^n/n!.
  • #1
magnifik
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Homework Statement


I am trying to find the Tn(x) for sqrt[x] centered at a=1


Homework Equations






The Attempt at a Solution


right now i have
f'(x)=1/2x^-1/2
f''(x)=-1/4x^-3/2
f'''(x)=3/8x^-5/2
f''''(x)=-15/16x^-7/2
f'(1)=1/2
f''(1)=-1/4
f'''(1)=3/8
f''''(1)=-15/16

how do i find the coefficient for the nth term?? i keep getting stuck
i tried n/2+1/(-2)^n.. doesn't work
or 1/(-2)^n*(n/2-1)...fail
help please
 
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  • #2


Hi there,

To find the coefficient for the nth term of Tn(x), you can use the Taylor series formula:

Tn(x) = f(a) + f'(a)(x-a) + f''(a)(x-a)^2/2! + f'''(a)(x-a)^3/3! + ... + f^(n)(a)(x-a)^n/n!

In this case, a=1 and f(x) = sqrt[x]. So, we have:

Tn(x) = sqrt[1] + 1/2(x-1) - 1/4(x-1)^2/2! + 3/8(x-1)^3/3! - 15/16(x-1)^4/4! + ... + (-1)^(n+1) * (2n-1)!! / 2^n * (x-1)^n/n!

where (2n-1)!! represents the double factorial.

I hope this helps! Let me know if you have any further questions.
 

1. What is a Taylor series expansion?

A Taylor series expansion is a mathematical representation of a function using an infinite sum of terms. It is used to approximate a function around a specific point by adding up the values of the function and its derivatives at that point.

2. Why is Taylor series expansion useful?

Taylor series expansion allows us to approximate a complex function with a simpler one, making it easier to analyze and manipulate mathematically. It also helps us to estimate the values of a function at points where the original function may not be easily evaluated.

3. What is the formula for a Taylor series expansion?

The general formula for a Taylor series expansion of a function f(x) around a point a is given by:
f(x) = f(a) + f'(a)(x-a) + f''(a)(x-a)^2/2! + f'''(a)(x-a)^3/3! + ...

4. What is the difference between Taylor series and Maclaurin series?

A Taylor series expansion is a generalization of the Maclaurin series, which is a special case of a Taylor series with a = 0. Therefore, all Maclaurin series are Taylor series, but not all Taylor series are Maclaurin series.

5. How do you determine the convergence of a Taylor series?

The convergence of a Taylor series depends on the function being approximated and the point of expansion. In general, a Taylor series will converge if the function is infinitely differentiable and the remainder term approaches 0 as the number of terms in the series increases. However, it is important to check for convergence using additional methods such as the ratio test or the integral test.

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