Question

What is the sum of the arithmetic sequence 3 9 15... If there are 24 terms brainly

Answer 1

Answer:

147 is the 24 term.

Step-by-step explanation:

Just add 6 to the number.....

3 + 6 = 9

9 + 6 = 15

next would be 21

and so on....

so, take 24 and multiply by 6

144 then add 3

147

Answer 2

Answer:

1728

Step-by-step explanation:

We have been given an arithmetic sequence. We are asked to find the sum of first 24 terms of our given sequence.

We will use arithmetic sequence sum formula to solve our given problem.

$S_n=\frac{n}{2}(2a+(n-1)d)$, where,

n = Number of terms,

a = First term of sequence,

d = Common difference between two terms.

$d=9-3=6$

$S_n=\frac{24}{2}(2(3)+(24-1)6)$

$S_n=12(6+(23)6)$

$S_n=12(6+138)$

$S_n=12(144)$

$S_n=1728$

Therefore, the sum of 24 terms of our given sequence would be 1728.