Question

are 7, 9, 11, 13 arithmetic or geometric numbers

Answer 1

when you add or subtract each time, to obtain the next term, it is an arithmetic sequence.
when you multiply (or divide) each time, to obtain the next term, it is a geometric sequence.

Answer 2

\(\large\color{black}{ 2,5,8,11,14 ... }\) is an arithmetic sequence, because you are adding 3 each time.

\(\large\color{black}{ 3,9,81,243.. }\) is a geometric sequence, because you are multiplying times 3 each time.