Computer Science Canada sequences and series |
| Author: | hamid14 [ Thu Jan 27, 2011 6:35 pm ] |
| Post subject: | sequences and series |
it says find the sum of the series : 3 - 6 + 12 - 24 + ... + 3072 I made a formula Sn = 3 * -2 (n-1) and the n-1 is an exponent but i cant figure out who to get the sum properly. thanks any help is appreciated. |
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| Author: | Insectoid [ Thu Jan 27, 2011 6:42 pm ] |
| Post subject: | RE:sequences and series |
Try writing out the first few values to generate a formula. sum(1) = 3 sum(2) = -3 sum(3) = 9 sum(4) = -15 ... With this information it's relatively straightforward to figure it out. |
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| Author: | hamid14 [ Thu Jan 27, 2011 6:52 pm ] |
| Post subject: | Re: sequences and series |
lmao sorry but im just not getting this. im actually trying to help someone else. |
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| Author: | RandomLetters [ Thu Jan 27, 2011 8:13 pm ] |
| Post subject: | RE:sequences and series |
It's pretty hard to explain how to find the formula. Use the basic exponential sequence tn = 2^(n-1) Then Sn = 2 + 4 + 8 + 16 ... tn then some magic happens And you get the formula Sn = a(1 - r^n)/(1-r) |
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| Author: | hamid14 [ Thu Jan 27, 2011 9:57 pm ] |
| Post subject: | Re: sequences and series |
lol great explanation jk. i got it >.> |
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| Author: | L.mawaty [ Sun Jan 30, 2011 10:20 pm ] |
| Post subject: | RE:sequences and series |
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