Find the sum of first 20 terms of these sequence whose nth term is 
.
Given, an= An + B
Put n = 1, a1= A + B
Put n = 20, a20= 20A + B
S20= 
[a + l]
= 10 [A + B + 20A + B]
= 10 [21A + 2B]
= 210A + 20B
25
Find the sum of first 20 terms of these sequence whose nth term is .
Given, an= An + B
Put n = 1, a1= A + B
Put n = 20, a20= 20A + B
S20= [a + l]
= 10 [A + B + 20A + B]
= 10 [21A + 2B]
= 210A + 20B