Question

Sum of 'n' terms of an AP is 3n square +6n
Then its 5th term is

(a) 33
(b) 64
(c) 32
(d) 31
​

Answer 1

Answer:

33

Step-by-step explanation:

Sn=3nsquare + 3n

a5=S5-S4

a5=S(5)square+6(5)-[3(4)square+6(4)]

a5=3(25)+30-[3(16)+24]

a5=105-72

a5=33

Answer 2

Answer:

We know that sum of n terms of an AP = d/2n² + (a-d/2)n

so d= 6 and a = 9

therefore 5th term of AP= a + (n-1)d

= 9 + 4×6

= 9+24= 33