Question

If the general term of an arithmetic sequence is t(n) = 7-3n , find the sum of the first 7 terms of the

Answer 1

Tn=7-3n
putting n=1,2,3,4,.......
AP:4,1,-2,-5.......
T7=7-21=-14.
S7=7/2[4+(-14)]. [Sn=n/2(a+T7)
=7/2(-10)=-35