Question

An arithmetic sequence is given below. 15, 18, 21, 24, ... Write an explicit formula for the n term a,. th​

Answer 1

`a_(n)` = 3n + 12

Explanation:

the nth term ( explicit formula ) of an arithmetic sequence is

`a_(n)` = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

here a₁ = 15 and d = a₂ - a₁ = 18 - 15 = 3 , then

`a_(n)` = 15 + 3(n - 1) = 15 + 3n - 3 = 3n + 12