Question

find the sum of first 8 multiples of 3​

Answer 1

first 8 multiple of 3 are 3,6,9,12,15,18

their sum= 3+6+9+12+15+18=63

Answer 2

$\huge\bold{HEYAA !!}$

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First multiple of 3 = 3 = a

8th multiple of 3 = 24 = l

And,

here d = 3

So,

A.P = 3, 6, 9, ....... , 24

As,

$S_n$ = $\frac{n}{2}$ ( $\text{a + l}$ )

$S_8$ = $\frac{8}{2}$ ( $3 + 24$ )

$S_8$ = 4 ( 27 )

$S_8$ = 108

...

So, the answer is 108.

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