Question

How many terms are in the arithmetic sequence 7, 1, −5, …, −161?

Answer 1

Answer:

29

Step-by-step explanation:

The n th term of an arithmetic sequence is

• $a_{n}$ = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

d = 1 - 7 = - 5 - 1 = - 6 and a₁ = 7, $a_{n}$ = - 161, hence

7 - 6(n - 1) = - 161 ← solve for n

7 - 6n + 6 = - 161

13 - 6n = - 161 ( subtract 13 from both sides )

- 6n = - 174 ( divide both sides by - 6 )

n = 29

There are 29 terms in the sequence