Question

Help plz consider the sequence {4,6,8,10...}Find the explicit formula that defines the sequence. A) an = 2n + 2 B) an = 2n + 4 C) an = 4n + 2 D) an = 4n + 4

Answer 1

A

this is an arithmetic sequence whose n th term ( explicit formula) is

$a_{n}$ = $a_{1}$ + (n - 1 )d

where d is the common difference and $a_{1}$ the first term

here d = 10 - 8 = 8 - 6 = 6 - 4 = 2 and $a_{1}$ = 4, hence

$a_{n}$ = 4 + 2(n - 1 ) = 4 + 2n - 2 = 2n + 2 → A