Geometric Sequence
Suppose that a, b and c is a geometric sequence, and a>b>c, then a/b=b/c.
a/b=b/c
For example, 1, 7 and 49 is a geometric sequence. The next number can be obtained by multiplying its previous number by a particular number.
Arithmetic Sequence
Suppose that a, b and c is an arithmetic sequence, and a>b>c, then a-b=b-c. They have a common difference, and let the common difference be x, then x=a-b=b-c. For example, 1, 2 and 3 is an arithmetic sequence, and their common difference is 2-1 as well as 3-2, that is, 1.
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