Answer:
geometric with r = [tex]\frac{1}{2}[/tex]
Step-by-step explanation:
An arithmetic sequence has a common difference (d) between consecutive terms
2 - 4 = - 2
1 - 2 = - 1
Then d is not common , not an arithmetic sequence
A geometric sequence has a common ratio (r ) between consecutive terms
2 ÷ 4 = 0.5
1 ÷ 2 = 0.5
Then common ratio r = [tex]\frac{1}{2}[/tex]
Thus sequence is geometric
