Question

given the sequence a(n)=-2(n)+4 find the 8th partial sum
i got 508 is that right or did i do something wrong

Answer 1

Does your assignment say anything about whether the sequence starts at n=0, or n=1?

Answer 2

no sadly it does not

Answer 3

starting at n=0, I am getting sum of -24. Starting at n=1, it is -40.

Answer 4

is the formula \[a_n=-2n+4\] ?

Answer 5

yep yep

Answer 6

i get a differnt result

Answer 7

OK, here are my partial sums
s0 = 4
s1 = 6
s2 = 6
s3 = 4
s4 = 0
s5 = -6
s6 = -14
s7 = -24 (8th partial sum)

Answer 8

well lets hear about it @akelos lol :) do you know where i went
wrong?

Answer 9

that makes a lot of sense b87

Answer 10

-24 is what i got as well

Answer 11

okidoki thanks guys

Answer 12

sorry b87 you were right -24 and -40

Answer 13

no problem alekos - thanks for checking!