Arithmetic sequences have a common difference between consecutive terms.
Geometric sequences have a common ratio between consecutive terms.
Let's compute the differences and ratios between consecutive terms:
Differences:
[tex]0.4-0.2 = 0.2,\quad 0.6-0.4=0.2,\quad 0.8-0.6=0.2,\quad 1-0.8=0.2[/tex]
Ratios:
[tex]\dfrac{0.4}{0.2}=2,\quad \dfrac{0.6}{0.4} = 1.5,\quad \dfrac{0.8}{0.6} = 1.33\ldots, \quad\dfrac{1}{0.8}=1.25[/tex]
So, as you can see, the differences between consecutive terms are constant, whereas ratios vary.
So, this is an arithmetic sequence.
