Question

find the sum of first n terms of the AP 6,4,2.......​

Answer 1

Answer:

here

a= 6

d = 4-6 = -2

Sn = n/2(2a+(n-1)*d)

= n/2(2*6+(n-1)*(-2))

= n/2(12-2n+2)

n/2(14-2n)

= n(7-n)

sun of first n terms = n(7-n)