Find the next three terms in the sequence
3, 12, 21, 30, . . .
4 answers
looks to me as the sequence is to add 9 to the last number...
Does anyone have all the answers
12 - 3 = 9
21 - 12 = 9
31 - 21 = 9
The common difference of successive members is 9
This is arithmetic progression.
In arithmetic progression:
an = a1 + ( n - 1 ) * d
In this case:
a1 = 3 , d = 9
an = a1 + ( n - 1 ) * d
an = 3 + ( n - 1 ) * 9
an = 3 + 9 n - 9
an = 9 n - 6
n = 1
a1 = 9 * 1 - 6 = 9 - 6 = 3
n = 2
a2 = 9 * 2 - 6 = 18 - 6 = 12
n = 3
a3 = 9 * 3 - 6 = 27 - 6 = 21
n = 4
a4 = 9 * 4 - 6 = 36 - 6 = 30
n = 5
a5 = 9 * 5 - 6 = 35 - 6 = 39
n = 6
a1 = 9 * 6 - 6 = 56 - 6 = 48
n = 7
a1 = 9 * 7 - 6 = 63 - 6 = 57
The next three terms:
39 , 48 , 57
21 - 12 = 9
31 - 21 = 9
The common difference of successive members is 9
This is arithmetic progression.
In arithmetic progression:
an = a1 + ( n - 1 ) * d
In this case:
a1 = 3 , d = 9
an = a1 + ( n - 1 ) * d
an = 3 + ( n - 1 ) * 9
an = 3 + 9 n - 9
an = 9 n - 6
n = 1
a1 = 9 * 1 - 6 = 9 - 6 = 3
n = 2
a2 = 9 * 2 - 6 = 18 - 6 = 12
n = 3
a3 = 9 * 3 - 6 = 27 - 6 = 21
n = 4
a4 = 9 * 4 - 6 = 36 - 6 = 30
n = 5
a5 = 9 * 5 - 6 = 35 - 6 = 39
n = 6
a1 = 9 * 6 - 6 = 56 - 6 = 48
n = 7
a1 = 9 * 7 - 6 = 63 - 6 = 57
The next three terms:
39 , 48 , 57
3,12,21,30,...if an = 201
4 answers