Question

What is the sum of the first 18 terms of the arithmetic series
11 + 15 + 19 + 23 + ⋯?

Answer 1

what property defines an arithmetic sequence?

Answer 2

exactly.. what is says...? A. 684 B. 810 C. 831 D. 846

Answer 3

in order to find the 18th term, you have to know what an arithmetic sequence is, how it is generated.

Answer 4

well, in order to find all the terms :) but the 18th term is important, or at least the rule to define it is

Answer 5

4?

Answer 6

hey this is an AP with a=11 and d=4

Answer 7

the rule would be to add 4 to each term to produce the next one yes

in this manner we could define all 18 terms if need be and just add them together ... other methods are more elegant, but they all amount to the same results