Answer
12,16,20,24
Work Step by Step
To find the first four terms of the sequence whose general term is $a_{n}$ = $a_{n-1}$ + 4, we replace n in the formula with 2,3, and 4.
n=1, $a_{1}$ = 12
n=2, $a_{2}$ =$a_{2-1}$ + 4 = $a_{1}$ + 4
Substitute $a_{1}$ as 12
$a_{2}$ = 12+4 = 16
n=3, $a_{3}$ =$a_{3-1}$ + 4 = $a_{2}$ + 4
Substitute $a_{2}$ as 16
$a_{3}$ = 16+4 = 20
n=4,$a_{4}$ =$a_{4-1}$ + 4 = $a_{3}$ + 4
Substitute $a_{3}$ as 20
$a_{4}$ = 20 + 4 = 24
The first four terms are 12,16,20,24.
