Question

What is the 13th term in the arithmetic sequence described by this explicit formula an=84+(n-1)(-6)

Answer 1

Just replace n with 13 in the formula: an=84+(n-1)(-6)

Thus, a(13)=84+(13-1)(-6) = 84 - 72 = 12 (answer)

Answer 2

12

Explanation:

The formula given is
`a_n=84+(n-1)(-6)`

Where
`a_n` gives the nth term

Since we want 13th term, we can say we want
`a_(13)` and we plug in 13 in
`n` into the formula. So we get:

`a_n=84+(n-1)(-6)\\a_(13)=84+(13-1)(-6)\\a_(13)=84+(12)(-6)\\a_(13)=84-72\\a_(13)=12`

So, the 13th term of the sequence is 12