Question

find the sum of first 24 terms of the list of number whose nth is given by an=3+2n

Answer 1

Hope this will help you ^_^

Answer 2

Given:

an=3+2n

Solution

an=3+2n

When n=1

a1 = 3+2 (1)

a1=3+2

a1=5

First term = 5

When n=2

a2 =3+2(2)

a2=3+4

a2=7

Common difference = a2-a1

=7-5

=2

a24=a+23d

=5+23 (2)

=5+46

=51

an=51

Sn=n/2(a+an)

=24/2 (5+51)

=12 (56)

=672

S24=672