# AP Calculus BC : Radius and Interval of Convergence of Power Series

## Example Questions

### Example Question #21 : Series In Calculus

Which of following intervals of convergence cannot exist?

For any , the interval for some  For any such that , the interval   Explanation: cannot be an interval of convergence because a theorem states that a radius has to be either nonzero and finite, or infinite (which would imply that it has interval of convergence ). Thus, can never be an interval of convergence.

### Example Question #1 : Radius And Interval Of Convergence Of Power Series

Find the interval of convergence of for the series .      Explanation:

Using the root test, Because 0 is always less than 1, the root test shows that the series converges for any value of x.

Therefore, the interval of convergence is: ### Example Question #1 : Taylor Series

Find the interval of convergence for of the Taylor Series .      Explanation:

Using the root test and . T

herefore, the series only converges when it is equal to zero.

This occurs when x=5.

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