Alternative sum formula for AP for JEE

Formula

\(S_n=\frac{n}{2}(a+l)\)

Variables: \(S_n\): sum of first \(n\) terms, \(a\): first term, \(l\): nth or last term.

Conditions: For an arithmetic progression with last term \(l=a_n\).

When first and last terms are known.