\(n^{th}\) term of an AP:
The \(n^{th}\) term \(a_{n}\) of the AP with first term 'a' and common difference 'd' is given by
 
\(a_{n} = a + (n – 1) d\).

\(a_{n}\) is also called the general term of the AP.
 
If there are m terms in the AP, then \(a_{m}\) represents the last term which is sometimes also denoted by \(l\).
 
Example:
 
If \(a = 7\), \(d = 3\) and \(n = 8\). Find \(a_{n}\).
 
Solution:
 
\(a_{n}\) can be found using the below formula,
 
\(a_{n} = a + (n – 1) d\)
 
Substituting the known values we get,
 
\(a_{n} = 7 + ( 8 - 1) 3 \)
 
\(= 7 + (7 \times 3)\)
 
\(= 7 + 21\)
 
\(= 28\)