The given sequence 8,11, 14, 17, 20, ... is an arithmetic sequence, the constat term is calculated by subtracting to consecutive terms, as follow:
11 - 8 = 3
Then, the general expression for the arithmetic sequence is:
an = 8 + 3n
where n =0,1,2,...
the 14th term is obtained when n = 13:
a13 = 8 + 3(13)
a13 = 8 + 39
a13 = 47
Hence, the 14th term is 47
