How do you tell whether the sequence #1, 2, 4, 7, 11# is arithmetic?
It is not an arithmetic sequence.
In an arithmetic sequence, the difference between a term and its immediately preceding term is always same.
Let use see here,
Here the difference is continuously increasing
Hence, it is not an arithmetic sequence.
Note: In an geometric sequence, the ratio of a term to its immediately preceding term is always same. This is not the case here as