Taylor Series Expansion and Radius of Convergence for $f(x)=x^4-3x^2+1$

In summary, a Taylor Series Expansion is a method of approximating a function with a polynomial using its derivatives at a specific point. The expansion is calculated by taking derivatives and creating a polynomial, with more terms resulting in a more accurate approximation. The Radius of Convergence is the distance from the center of the expansion to the closest point where it accurately approximates the function, and it is determined using the Ratio Test. For the function f(x) = x^4-3x^2+1, the Radius of Convergence is infinite, meaning the expansion will converge for all values of x.
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find the taylor series for $f(x)=x^4-3x^2+1$ centered at $a=1$. assume that f has a power series expansion. also find the associated radius of convergence.

i found the taylor series. its $-1-2(x-1)+3(x-1)^2+4(x-1)3+(x-1)^4$ but how do i find the radius of convergence?
 
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  • #2
Since your Taylor series is a polynomial in $x$ (or $x-1$), it converges for all $x$. So the radius of convergence is $(-\infty, \infty)$.
 

1. What is a Taylor Series Expansion?

A Taylor Series Expansion is a way of approximating a function with a polynomial by using its derivatives at a specific point. It is used to calculate the values of a function at any point within its interval of convergence.

2. How is the Taylor Series Expansion calculated?

The Taylor Series Expansion is calculated by taking the derivatives of the function at a specific point and using those derivatives to create a polynomial. The more terms included in the polynomial, the more accurate the approximation will be.

3. What is the Radius of Convergence?

The Radius of Convergence is the distance from the center of a Taylor Series Expansion to the closest point where the series still accurately approximates the function. It is represented by the variable R and determines the interval of convergence for the series.

4. How is the Radius of Convergence determined?

The Radius of Convergence is determined by using the Ratio Test, which compares the absolute value of the ratio of consecutive terms in the series to the limit as n approaches infinity. If the limit is less than 1, the series converges and the value of R can be found by taking the reciprocal of the limit.

5. What is the Radius of Convergence for the function f(x) = x^4-3x^2+1?

The Radius of Convergence for this function is infinite since it is a polynomial. This means that the Taylor Series Expansion for this function will converge for all values of x.

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