Question

If the sum of the first n terms of an A.P is 2n square+n,find 6th terms

Answer 1

Answer:78

Step-by-step explanation: Sn=2n square + n

                                             S6  =2 x 6X6 + n

                                                    =2 x 36 + 6

                                                    =78

Answer 2

Sn = 2n²+n

⇒ S6 = 2(6)²+6 = 78

⇒ S5 = 2(5)²+5 = 55

We know that,

an = Sn - Sn-1

⇒ a6 = S6 - S5

= 78 - 55

= 23

HOPE IT HELPS :-)