Math Problem Statement

Find the song to Infinity of the geometric progression with the first three terms 0.5, 0.5³ and 0.5⁵.

Solution

To find the sum to infinity of a geometric progression (GP), we use the formula:

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

Where:

  • SS_{\infty} is the sum to infinity,
  • aa is the first term of the series,
  • rr is the common ratio of the series, provided that r<1|r| < 1 for the sum to infinity to exist.

Step 1: Identify the terms and common ratio

The first three terms of the GP are given as:

  • First term a=0.5a = 0.5,
  • Second term 0.53=0.1250.5^3 = 0.125,
  • Third term 0.55=0.031250.5^5 = 0.03125.

To find the common ratio rr, we divide the second term by the first term:

r=0.530.5=0.1250.5=0.25r = \frac{0.5^3}{0.5} = \frac{0.125}{0.5} = 0.25

So, the common ratio is r=0.25r = 0.25.

Step 2: Apply the sum to infinity formula

Now, substitute a=0.5a = 0.5 and r=0.25r = 0.25 into the formula for the sum to infinity:

S=0.510.25=0.50.75=11.5=23S_{\infty} = \frac{0.5}{1 - 0.25} = \frac{0.5}{0.75} = \frac{1}{1.5} = \frac{2}{3}

Final Answer:

The sum to infinity of the geometric progression is:

S=23S_{\infty} = \frac{2}{3}

Would you like more details on any step, or have any further questions?


Here are some related questions:

  1. What happens if the common ratio rr is negative or larger than 1?
  2. Can we find the sum to infinity if r1|r| \geq 1?
  3. How do we calculate the sum of the first nn terms of a geometric progression?
  4. What is the relationship between geometric progressions and exponential functions?
  5. How does a geometric series differ from an arithmetic series?

Tip: The sum to infinity formula only works when the absolute value of the common ratio is less than 1, as larger ratios make the series diverge.

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Math Problem Analysis

Mathematical Concepts

Algebra
Geometric Progression
Series and Sequences

Formulas

Sum to infinity of a geometric series: S∞ = a / (1 - r)
Common ratio: r = second term / first term

Theorems

Sum to infinity of a geometric series theorem

Suitable Grade Level

Grades 9-12