Math Problem Statement

If the following infinite geometric series converges, find its sum. [\large\displaystyle\sum\limits_{k=0}^{{\infty}}{{{2(3)^{k}}}} = ]

Solution

To determine if the infinite geometric series converges and to find its sum, we first need to identify the first term aa and the common ratio rr of the series.

The given series is:

k=02(3)k\sum\limits_{k=0}^{\infty} 2(3)^k

This can be expressed as:

2+2(3)+2(32)+2(33)+2 + 2(3) + 2(3^2) + 2(3^3) + \dots

Identifying aa and rr

  • The first term aa of the series is the value of the expression when k=0k = 0: a=2(3)0=2a = 2(3)^0 = 2
  • The common ratio rr is the factor by which each term is multiplied to get the next term: r=3r = 3

Convergence Condition

For an infinite geometric series to converge, the common ratio rr must satisfy: r<1|r| < 1 Here, r=3r = 3, and since 3>1|3| > 1, the series does not converge.

Conclusion

Since the common ratio r=3r = 3 does not satisfy the convergence condition r<1|r| < 1, the given infinite geometric series diverges and therefore does not have a sum.

Would you like more details or have any questions? Here are some related questions to explore:

  1. What happens when the common ratio rr is negative?
  2. How do you find the sum of a convergent geometric series?
  3. Can you provide an example of a convergent geometric series?
  4. How do you calculate the sum of a finite geometric series?
  5. What is the formula for the sum of an infinite geometric series?

Tip: In any geometric series, always check the common ratio rr first to determine whether the series converges or diverges.

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Math Problem Analysis

Mathematical Concepts

Infinite series
Geometric series
Convergence criteria

Formulas

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Theorems

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Suitable Grade Level

High school and above