Question

What is the rule of the sequence `1.5, 3.9, 6.3, 8.7 ...`?

Answer 1

This is an arithmetic sequence with initial term `1.5` and common difference `2.4`.

`a_n = 1.5 + 2.4(n-1)`

Explanation:

Notice that the difference between any pair of successive terms is `2.4`. So this is an arithmetic sequence.

The standard formula for the term of an arithmetic sequence is:

`a_n = a + d(n-1)`

where `a` is the initial term and `d` the common difference.