Answer:
geometric sequence
Step-by-step explanation:
an arithmetic sequence has a common difference d between consecutive terms.
21 - 147 ≠ 3 - 21
Hence the sequence is not arithmetic
A geometric sequence has a common ratio r between consecutive terms
[tex]\frac{21}{147}[/tex] = [tex]\frac{1}{7}[/tex] and [tex]\frac{3}{21}[/tex] = [tex]\frac{1}{7}[/tex]
there is a common ratio thus the sequence is geometric