Question

find the sum of first 8 multiply of 3

Answer 1

We know that first three multiples of 8 are 8 , 16 , 24

a=8

d=8

n=3

Sn=n/2 [2a+(n-1)d]

S3=3/2 [2(8)+(3-1)8]

S3=3/2[16+16]

S3=3/2[32]

S3=3(16)

S3=48

Hope this helps

Answer 2

The answer is 108. so we can also use formula n/2(2a+(n-1)d).