The domain is

and the range is

Domain is x values (horizontal axis), while range is y values (vertical axis). On a line like this one, domain is calculated from the left most point to the right most, while range is calculated from the down most to the upmost.
Because this line is a solid line rather than a dotted line, less than or equal to

signs are used rather than just

less than signs.
Answer:
8*2^(n-1)
Step-by-step explanation:
This is a geometric sequence since we multiply from the previous term.
a_n = a_1 * common ratio^(n-1) where a_n is the nth number and a_1 is the first.
The first term is 8, so we have
a_n = 8*<common ratio>^(n-1) = 8*2^(n-1)