Question

the sum of first 'a' terms of arithmetic progrenssion in given by formula Sn=3n²+n then it's 3rd term is
a)14 b)16 c)22 d)42​

Answer 1

Answer:

16

Step-by-step explanation:

Sn= 3n²+n

S1= 3x1²+1 = 4

S2= 3x2²+2= 14

S3= 3x3²+3= 30

-

-

-

-

Sn= 3n²+n

Term1 or T1 = 4 = S1

T2 = S2 - S1 = 14 - 4= 10

T3= S3 - S2 = 30- 14 = 16