Question

Find the recursive formula for 18, 15, 12, 9, . .

Answer 1

Answer: $a_{n}=a_{n-1}-3$  ,  $n\geq 2$

Step-by-step explanation:

$a_{1}$ = 18

The common difference = -3

Therefore :

$a_{n}=a_{n-1}-3$  ,  $n\geq 2$

check:

when n = 2

$a_{2}= a_{1}-3$

$a_{2}=18-3 = 15$