Question

find the sum of first 8 multiples of 3 using ap

Answer 1

the sum of first multiple of 3

is =

AP => 3, 6,9 .....

n=> 8

d => 6-3 => 3

now ,

sn => n/ 2 ( 2a+ (n-1) d

=> 8/2 ( 2*3 + ( 8-1) *3

4 ( 6 + 21 )

=> 4* 27

=> 108 .

Answer 2

a=3,d=3,n=8

sn=n/2(2a+(n-1)d)
=8/2(2*3+(8-1)3)
=4(6+21)
=4*27=108