Question

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

Answer 1

a1=5 (by putting n=1)
a2=7 a3=9,........a24=51......
s=(n/2)(a+l)
s=12(5+51)...ans

Answer 2

the nth term is an=3+2n so by using this we can find the value of terms like a1=5,a2=7,a3=9
and a24=51
now the first term is 5 and the last term is 51 and the difference is 2
by using the formula for sum of n terms i. e
sn =n/2(2a+(n-1)d)
so s24=24/2(10+23*2) i. e 672 ans....