Question

What is the sum of the arithmetic sequence 8,14,20... , if there are 22 terms? answers to choose from.

a)1,558
b)1,560
c)1,562
d)1,564

Answer 1

@spectrum

Answer 2

[8 + (0)(6)] + [8 + (1)(6)] + [8 + (2)(6)] + ... + [8 + (21)(6)] =
(22)(8) + (6)(21)(22)/2
1 + 2 + 3 + ... + (n - 1) + n = n(n + 1)/2

Answer 3

okay i believe the answer is 1,560 is this correct?

Answer 4

no

Answer 5

well i wonder what i did wrong?? then it has to be 1,562 it is the closest to the answer i got right

Answer 6

All the answers are 2 apart, so don't go by "closeness". Suppose you weren't given any choices and had nothing to choose from and had to get it by scratch.

I already worked out the problem for you:

(22)(8) + (6)(21)(22)/2

Just multiply it out. No guessing!

Answer 7

i got 1,474 but that isnt any of the answers i posted:(

Answer 8

If you are having problems with multiplying, I can't help you. Good luck.

Answer 9

oh i see what i did wrong for got to divide @tcarroll010 thankyou

Answer 10

answer : 1562