Question
\begin{tabular}{|l|l|} Write the arithmetic sequence \( -14,-11,-8,-5, \ldots \) in the standard form: \\ \( a_{n}=\square \) Preview \end{tabular}\( | \)
Ask by Ellis Norris. in the United States
Dec 06,2024
Real Tutor Solution
Tutor-Verified Answer
Answer
\( a_n = 3n - 17 \)
Solution
To write the arithmetic sequence \( -14, -11, -8, -5, \ldots \) in standard form, we first need to identify the first term and the common difference.
1. **First term (\( a_1 \))**: The first term of the sequence is \( -14 \).
2. **Common difference (\( d \))**: To find the common difference, we subtract the first term from the second term:
\[
d = -11 - (-14) = -11 + 14 = 3
\]
Now that we have the first term and the common difference, we can write the general term of the arithmetic sequence in standard form. The formula for the \( n \)-th term of an arithmetic sequence is given by:
\[
a_n = a_1 + (n - 1) \cdot d
\]
Substituting the values we found:
- \( a_1 = -14 \)
- \( d = 3 \)
The formula becomes:
\[
a_n = -14 + (n - 1) \cdot 3
\]
Now, we can simplify this expression:
\[
a_n = -14 + 3(n - 1)
\]
\[
a_n = -14 + 3n - 3
\]
\[
a_n = 3n - 17
\]
Thus, the standard form of the arithmetic sequence is:
\[
a_n = 3n - 17
\]
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The first term of the sequence is \( a_1 = -14 \). The common difference, \( d \), can be identified by subtracting the first term from the second term: \( -11 - (-14) = 3 \). Using the formula for the \( n \)-th term of an arithmetic sequence, \( a_n = a_1 + (n - 1)d \), we can substitute the values: \[ a_n = -14 + (n - 1) \cdot 3 \] Simplifying this gives: \[ a_n = -14 + 3n - 3 = 3n - 17 \] Thus, the standard form is: \[ a_n = 3n - 17 \]