Question

In an arithmetic progression - 18,13,8,3,...,S35=

Answer 1

Answer:

a=18, d= -5. S35= a+34d= 18+34(-5)= -152.22

Answer 2

Answer:

a=18

d=13-18

= -5

sn=. n/2+(a)+(n+1)d

35= n/2 +18+(n-1)