Question

The sum of first'n' terms of an arithemetie progression is given by the formula
S = 3n+n, then its 3rd term is
A 14
B. 16
D. 42
C 22​

Answer 1

Answer:

(B) 16

Step-by-step explanation:

S = 3n^2 +n

S(1) = 3+1 =4

S(2) =3×4 +2 = 12+2 =14

S(3) = 3×9 +3 =27 +3 = 30

T(1) = S(1) = 4

T(2) = S(2) - S(1) =14 - 4 = 10

T(3) = S(3) - S(2) =30 - 14 = 16