Chapter 14: Problem 12
Write the first five terms of each geometric sequence with the given first term, \(a_{1},\) and common ratio, \(r .\) $$a_{1}=24, r=\frac{1}{3}$$
Short Answer
Expert verified
The first five terms of the geometric sequence are: 24, 8, \(\frac{8}{3}\), \(\frac{8}{9}\), \(\frac{8}{27}\).
Step by step solution
01
Understand the Problem
We have a geometric sequence with the first term \(a_{1}\) as 24 and the common ratio \(r\) as \(\frac{1}{3}\). We need to write the first five terms of the sequence.
02
Calculate the second term
We will calculate the second term (\(a_{2}\)) by plugging in \(n = 2\) into the formula \(a_{n}\) = \(a_{1} \cdot r^{(n-1)}\). Thus \(a_{2}\) = \(24 \cdot \left(\frac{1}{3}\right)^{(2-1)}\) which equals 8.
03
Calculate the third term
Calculate the third term (\(a_{3}\)) using the same formula but replacing \(n\) with 3. Thus \(a_{3}\) = \(24 \cdot \left(\frac{1}{3}\right)^{(3-1)}\) which equals \( \frac{8}{3}\).
04
Calculate the fourth term
Same way, calculate the fourth term (\(a_{4}\)) using the formula and substituting \(n\) with 4. Thus \(a_{4}\) = \(24 \cdot \left(\frac{1}{3}\right)^{(4-1)}\) which equals \( \frac{8}{9}\).
05
Calculate the fifth term
Lastly, calculate the fifth term (\(a_{5}\)) by substituting \(n\) with 5 in the formula. Thus \(a_{5}\) = \(24 \cdot \left(\frac{1}{3}\right)^{(5-1)}\) which equals \( \frac{8}{27}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the First Term
The first term in a geometric sequence is the starting number from which the sequence is generated. It's often symbolized as \(a_1\). It serves as the foundation of the entire sequence. In our given exercise, the first term \(a_1\) is 24.
- Imagine the first term as your starting point or the initial step in a journey of numbers.
- Knowing the first term is crucial because every subsequent term in the sequence is built upon it.
- Without the first term, it would be impossible to generate the rest of the sequence accurately.
Decoding the Common Ratio
The common ratio of a geometric sequence is the factor by which we multiply the current term to get the next term. In this exercise, the common ratio \(r\) is \(\frac{1}{3}\).
- The common ratio plays a vital role in determining how the sequence progresses.
- If the ratio is greater than 1, the sequence will grow larger. Conversely, if it's between 0 and 1, the sequence decreases.
- A negative common ratio means the terms will alternate between positive and negative.
Exploring the Sequence Formula
The sequence formula is a mathematical expression used to find any term in a geometric sequence. The standard formula is given by:\[a_n = a_1 \cdot r^{(n-1)}\]
- \(a_n\) represents the \(n^{th}\) term of the sequence.
- The formula uses both the first term and the common ratio to find any term positionally.
Comprehending a Mathematical Sequence
A mathematical sequence refers to an ordered list of numbers following a specific pattern or rule. Geometric sequences are a type of mathematical sequence where each term is obtained by multiplying the previous term by a constant called the common ratio.
- Sequences can be finite or infinite, depending on how many terms they include.
- They are used in various fields, like computer science, finance, and physics, to model repetitive processes.
- Beyond their mathematical utility, sequences help in understanding patterns and structures.