Question

suppose that a sequence is defined as follows.
( a_1 = 20 ),
( a_n = a_{n - 1} - 8 ) for ( n geq 2 )
list the first four terms of the sequence.

Explanation:

Step1: Identify first term

$a_1 = 20$

Step2: Calculate second term

Substitute $n=2$: $a_2 = a_{1} - 8 = 20 - 8 = 12$

Step3: Calculate third term

Substitute $n=3$: $a_3 = a_{2} - 8 = 12 - 8 = 4$

Step4: Calculate fourth term

Substitute $n=4$: $a_4 = a_{3} - 8 = 4 - 8 = -4$

Answer:

The first four terms are $20$, $12$, $4$, and $-4$