If the series is made up of numbers in an arithmetic progression, you have

where

is the first term and

is the common difference between terms.
Since the last term in the series is

, you have

Solve the system

and you'll find that the first term is

(with

).
The characteristics of these geometric figures create:
1. Parallel lines are lines in the same plane that will never intersect and also if they are in different planes, those lines will never intersect too.
2. While perpendicular lines are two lines that will meet at a 90-degree angle or right angle.
<span>10!/5! =10*9*8*7*6=30,240;;
If order is not considered, 10C5 =10!/5!5!=252 </span>
Answer:

You can plug it into a graphing website or calculator to double check