Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
9. Sequences, Series, & Induction
Geometric Sequences
Problem 31a
Textbook Question
In Exercises 31–34, write the first five terms of each geometric sequence. a1 = 3, r = 2
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1
Identify the first term of the geometric sequence, which is given as \( a_1 = 3 \).
Recognize that the common ratio \( r \) is given as 2.
Use the formula for the \( n \)-th term of a geometric sequence: \( a_n = a_1 \cdot r^{n-1} \).
Calculate the second term: \( a_2 = 3 \cdot 2^{2-1} = 3 \cdot 2 \).
Continue this process to find the next three terms: \( a_3 = 3 \cdot 2^{3-1} \), \( a_4 = 3 \cdot 2^{4-1} \), and \( a_5 = 3 \cdot 2^{5-1} \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Geometric Sequence
A geometric sequence is a sequence of numbers where each term after the first is found by multiplying the previous term by a fixed, non-zero number called the common ratio. This type of sequence can be expressed in the form a_n = a_1 * r^(n-1), where a_n is the nth term, a_1 is the first term, r is the common ratio, and n is the term number.
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First Term (a1)
The first term of a geometric sequence, denoted as a1, is the initial value from which the sequence begins. In the given problem, a1 = 3 indicates that the first term of the sequence is 3, which serves as the foundation for calculating subsequent terms using the common ratio.
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Common Ratio (r)
The common ratio, denoted as r, is the factor by which each term in a geometric sequence is multiplied to obtain the next term. In this case, r = 2 means that each term will be double the previous term, allowing for the generation of the sequence's subsequent values based on the first term.
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