Chapter 15: Problem 31
Find the indicated term for each arithmetic sequence. $$a_{1}=-5, d=4 ; a_{16}$$
Short Answer
Expert verified
The 16th term of the arithmetic sequence is \(a_{16}=55\).
Step by step solution
01
Write down the formula for finding the nth term of an arithmetic sequence
The formula for finding the nth term of an arithmetic sequence is:
\(a_n = a_1 + (n-1)d\)
02
Plug in the given values
We have \(a_1 = -5\), d = 4, and n = 16, so we plug these values into the formula:
\(a_{16} = -5 + (16-1) \cdot 4\)
03
Simplify the expression
First, we'll simplify the expression inside the parentheses and then multiply by the common difference:
\(a_{16} = -5 + (15) \cdot 4\)
Next, we'll multiply 15 by 4:
\(a_{16} = -5 + 60\)
04
Calculate the final result
Finally, we'll add -5 and 60 to get the 16th term of the arithmetic sequence:
\(a_{16} = 55\)
So, the 16th term of this arithmetic sequence is 55.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
nth term formula
The **nth term formula** is a powerful tool to find any term in an arithmetic sequence without listing all the preceding terms. This formula is given by:
- \(a_n = a_1 + (n-1)d\)
common difference
In any arithmetic sequence, the **common difference** is a fixed number that you add to each term to get the next term. It is denoted by \(d\). For example, if your sequence starts at -5 and the common difference \(d\) is 4, each subsequent term will be 4 units larger than the previous one. Think of the common difference as the step size or the gap between consecutive terms:
- If \(d > 0\), the sequence is increasing.
- If \(d < 0\), the sequence is decreasing.
- If \(d = 0\), all terms are the same.
sequence term calculation
**Sequence term calculation** is the process of determining a specific term in an arithmetic sequence using the parameters of the sequence. Here’s a step-by-step guide using the nth term formula:
1. Identify \(a_1\) and \(d\), the first term and common difference of the sequence.
2. Choose the term number \(n\) you want to find.
3. Substitute these values into the nth term formula: \(a_n = a_1 + (n-1)d\).
4. Simplify the expression to find the desired term.
This procedural approach ensures accuracy and allows you to solve even complex problems without confusion.
1. Identify \(a_1\) and \(d\), the first term and common difference of the sequence.
2. Choose the term number \(n\) you want to find.
3. Substitute these values into the nth term formula: \(a_n = a_1 + (n-1)d\).
4. Simplify the expression to find the desired term.
This procedural approach ensures accuracy and allows you to solve even complex problems without confusion.
finding terms in a sequence
**Finding terms in a sequence** means understanding the pattern and using it to determine specific terms. Using the nth term formula is often the most straightforward method.To find a term:
- Start with the first term \(a_1\) of the sequence.
- Identify the common difference \(d\).
- Plug these values into \(a_n = a_1 + (n-1)d\).
- Perform the arithmetic calculations.