Concept Let us consider sequence a1,a2,a3...an is an A.P. Common difference " d′′=a2−a1=a3−a2=...=an−an−1 nth term of the A.P. is given by an=a+(n−1)d Sum of the first n terms =S=(n∕2)[2a+(n−1)×d]=(n∕2)(a+1) Where, a= First term, d= Common difference, n= number of terms, an=nth term, 1= Last term Calculation: Given, a0=2...(1) S5=