Question

Write the formula that represents the arithmetic sequence -15,-11,-7,-3,1,4,

Answer 1

`a_(n)` = 4n - 19

Explanation:

the arithmetic sequence should have 5 as 6th term, not 4

the nth term of an arithmetic sequence is

`a_(n)` = a₁ + d(n - 1)

where a₁ is the first term and d the common difference

here a₁ = - 15

and d = a₂ - a₁ = - 11 - (- 15) = - 11 + 15 = 4

Then explicit formula is

`a_(n)` = - 15 + 4(n - 1) = - 15 + 4n - 4 = 4n - 19