The sum of first 16 terms of the AP 10, 6, 2, ….. is


Given,


First term, a = 10


Common Difference, d = 6 - 10 = - 4(a2 - a1)


Using the formula,



Where Sn is the sum of first n terms


n = no of terms


a = first term


d = common difference


S16 = (16/2)[ 2(10) + (16 - 1) (- 4)]


= 8(20 - 60)


= - 320

16
1