27. Exercise problem XXII

If the sum of the first \(n\) terms of an AP is \(4n − n^2\), what is the first term (that is \(S_1\))? What is the sum of first two terms? What is the second term? Similarly find the \(3^{\text{rd}}\), the\(10^{\text{th}}\) and the \(n\)th terms.  

 

\(S_1=\)

 

\(S_2=\)

 

\(a_3=\)

 

\(a_{10}=\)

 

\(a_n=\) $i-ii$