Question

Which term of the A. P 21, 18,15,...is-81?state with reason is there any term 0 in this A. P

Answer 1

AP - 21,18,15.....is -81

a = t1 = 21

d = 3 , tn = -81

tn = a +( n - 1)d _(formula)

-81= 21 + (n - 1) 3

-60 (n - 1) 3

(n - 1) =

$\frac{ - 60}{3}$

n = -21

THERE IS NO "0" TERM IN AP....