#### Answer

Therefore the sequence is arithmetic as the common difference of the consecutive terms is a constant which is 9.

#### Work Step by Step

When a pattern is observed in the sequence the sequence is said to be arithmetic. In an arithmetic sequence, the difference between consecutive terms is constant.
The sequence is given: 11, 20, 29, 38, ...
Difference of first and second term:
20-11=9
Difference of second and third term:
29-20=9
Difference of third and fourth term:
38-29=9
Therefore the sequence is arithmetic as the common difference of the consecutive terms is a constant which is 9.