Question

Find the sum of the first 15 multiples of 8is the sum of first 100multiples of 8

Answer 1

Answer:

Sum of first 15 multiples of 8 is

8+16+24+32+40+48+56+64+72+80+88+96+104+112+120=960

Answer 2

Answer:

a = 8

n = 15

d = 8

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

= 15/2 (2×8 + (14)8]

= 15/2 [16 +112]

= 15/2 [128]

= 15 [64]

= 960