Math Problem Statement

12, 6, 3, 3/2, 3/4 find the sum of the infinite geometric series

Solution

To find the sum of an infinite geometric series, we use the formula:

S=a1rS_{\infty} = \frac{a}{1 - r}

where:

  • aa is the first term of the series,
  • rr is the common ratio, and
  • r<1|r| < 1 (this ensures the series converges).

Step 1: Identify the first term and common ratio.

  • The first term, a=12a = 12.
  • To find the common ratio rr, divide the second term by the first term: r=612=12r = \frac{6}{12} = \frac{1}{2}

Step 2: Apply the formula for the sum of an infinite geometric series.

Since r=12r = \frac{1}{2}, the series converges, and we can calculate the sum:

S=12112=1212=12×2=24S_{\infty} = \frac{12}{1 - \frac{1}{2}} = \frac{12}{\frac{1}{2}} = 12 \times 2 = 24

Final Answer:

The sum of the infinite geometric series is 2424.

Would you like further details or have any questions?


Here are 5 related questions to expand on this topic:

  1. What happens if the common ratio rr is greater than or equal to 1?
  2. How do we find the sum of a finite geometric series?
  3. Can an infinite series have a negative common ratio? If so, how does it affect the sum?
  4. What is the common ratio if the second term of the geometric series was 9 instead of 6?
  5. How does the geometric series formula change for series starting with a different term than 1?

Tip: Always verify the common ratio before applying the infinite series formula, as the series converges only when r<1|r| < 1.

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Math Problem Analysis

Mathematical Concepts

Algebra
Geometric Series
Infinite Series

Formulas

Sum of infinite geometric series: S_∞ = a / (1 - r)

Theorems

The infinite geometric series converges if |r| < 1

Suitable Grade Level

Grades 9-12