Find a formula for the [tex]$n$[/tex]th term of the arithmetic sequence.

First term: [tex]\(-12\)[/tex]

Common difference: [tex]\(4\)[/tex]

[tex]\[
a_n = -12 + (n-1) \cdot 4
\][/tex]



Answer :

To find the [tex]\(n\)[/tex]th term of an arithmetic sequence, we can use the formula:

[tex]\[ a_n = a_1 + (n - 1) \cdot d \][/tex]

where:
- [tex]\(a_n\)[/tex] is the [tex]\(n\)[/tex]th term of the sequence,
- [tex]\(a_1\)[/tex] is the first term of the sequence,
- [tex]\(n\)[/tex] is the position of the term in the sequence,
- [tex]\(d\)[/tex] is the common difference between consecutive terms.

Given:
- The first term [tex]\(a_1 = -12\)[/tex],
- The common difference [tex]\(d = 4\)[/tex].

Now we'll substitute these values into the formula:

1. Write down the general formula for the [tex]\(n\)[/tex]th term:
[tex]\[ a_n = a_1 + (n - 1) \cdot d \][/tex]

2. Substitute [tex]\(a_1 = -12\)[/tex] and [tex]\(d = 4\)[/tex] into the formula:
[tex]\[ a_n = -12 + (n - 1) \cdot 4 \][/tex]

3. Simplify the expression inside the parentheses:
[tex]\[ a_n = -12 + 4n - 4 \][/tex]

4. Combine like terms:
[tex]\[ a_n = 4n - 16 \][/tex]

So, the formula for the [tex]\(n\)[/tex]th term of the arithmetic sequence is:

[tex]\[ a_n = 4n - 16 \][/tex]

In the form [tex]\(a_n = mn + b\)[/tex], we have:

[tex]\[ a_n = 4n - 16 \][/tex]

Therefore, our final answer is:

[tex]\[ a_n = 4n - 16 \][/tex]