I just need someone to check my answer:

What is the sum of the arithmetic sequence 3, 9, 15 ..., if there are 24 terms?

a) 1452

b) 1728 (my answer)

c) 2028

d) 2268

Question

Mathematics

Urijah Bray

11 October, 13:54

I just need someone to check my answer:

What is the sum of the arithmetic sequence 3, 9, 15 ..., if there are 24 terms?

a) 1452

b) 1728 (my answer)

c) 2028

d) 2268

+3

Answers (1)

Know the Answer?

Konnor Frank · Answer 1

Sum is n (an+a1) / 2

an=a1+d (n-1)

common differnce is 6

first term si 3

an=3+6 (n-1)

24th term

a24=3+6 (24-1)

a24=3+6 (23)

a24=3+138

a24=141

so nth term is 141

n=24

24 (3+141) / 2=12 (144) = 1728

answer is B

I just need someone to check my answer:What is the sum of the arithmetic sequence 3, 9, 15 ..., if there are 24 terms?a) 1452b) 1728 (my answer)c) 2028d) 2268

I just need someone to check my answer:

What is the sum of the arithmetic sequence 3, 9, 15 ..., if there are 24 terms?

a) 1452

b) 1728 (my answer)

c) 2028

d) 2268