Question

If the sum of the first n terms of an arithmetic
progression is 7n2 + 2n, then the sum of its
third and fifth terms is​

Answer 1

Answer:

noooooooooooooooooooooooooooo

Step-by-step explanation:

1. noooooooooooooooooooooooooooo noooooooooooooooooooooooooooo noooooooooooooooooooooooooooo oo
2. noooooooooooooooooooooooooooo

Answer 2

Answer:

Ans: 102

Step-by-step explanation:

Given sum of first n terms

=7n²+2n

$3^{rd } \ term \ A_3= S_3-S_2\\\\5^{th } \ term \ A_5= S_5-S_4\\\\Thus \ sum \ of \ third \ and \ fifth \ term \ is\\\\=A_3 + A_5 =(S_3+S_5) - (S_2+S_4)\\\\= [ 7(3^)^2 +2(3)+7(5)^2+2(5) ]-[7(2)^2+2(2)+7(4)^2+2(4) ]\\\\=(63+6+175+10) - (28+4+112+8)\\\\=254-152\\\\=102$