(Q8).Find the sum of first 24 terms of the list of numbers whose nth term is given by an = 3 + 2n

As an = 3 + 2n

so, a1 = + =

a2 = + × =

a3 = + × =

List of numbers becomes 5, 7, 9, 11, . . .

Here, 7 – 5 = 9 – 7 = 11 – 9 = and so on

So, it forms an AP with common difference d = .

To find S24, we have n = , a = , d =

Therefore, S24 =
2
 [2 × + ( - 1) × ] = ( + ) =

So, sum of first 24 terms of the list of numbers is .