Question

find the sum of first 18term of an a. p whose n th term is 3-2n​

Answer 1

Step-by-step explanation:

nth term is given by 3-2n

so

a1=3-2=1

a2=3-4=-1

a3=3-6=-3

d=a2-a1=a3-a2=-2

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

S18=18/2[2+17(-2)]

=9[2-34]

=9[-32]

=-288

hope it helps

gd night

happy navratri