Question

Sum of nth term of an AP is given by Sn=3n^2/2 +n/2 then find its 5th term.

Answer 1

Answer:

14

Step-by-step explanation:

Sn = 3n²/2+n/2

If n = 1

S1 = 3/2 + 1/2 = 4/2 = 2

S1 = a = 2

If n = 2

S2 = 3(4)/2 + 2/2 = 6+1 =7

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

S2 = 2/2(2×2 + (1-1)d)

7 = 4 + d

7-4 =d

d = 3

a5 = 2 + (5-1)3

= 2 + 4×3

= 2 + 12

= 14