I realize that each one is n^3 but i don't know why all the even numbers are positive and the odds are negatives...please help?
2007-11-23 05:50:17 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
To get alternating signs just append (-1)^k onto the term. So sigma((-1)^k * n^k), k=1..9), or in a simpler form, sigma((-n)^k, k=1..9)
2007-11-23 05:58:13 · answer #1 · answered by Letao12 4 · 0⤊ 0⤋
With each of the odd cubes negative, you'll need a (-1)^n in there... keeping odd values of n negative, but even ones positive. Your series is:
{SIGMA} [for n = 1 to 9] {(-1)^n}{n^3}.
2007-11-23 14:02:43 · answer #2 · answered by Louise 5 · 0⤊ 0⤋
You use the alternator -1^(n) for alternating series. So your series term is [-1^j ]x j^3
2007-11-23 14:01:02 · answer #3 · answered by cattbarf 7 · 0⤊ 0⤋
it sounds like you homework but i think i got it wrong its -810
2007-11-23 14:00:34 · answer #4 · answered by evildragon100 2 · 0⤊ 0⤋