WiLBoY Posted September 27, 2008 Share Posted September 27, 2008 cool, yeah it's just two geometric series and then a bit of algebra. Link to comment Share on other sites More sharing options...
believe_in_blue Posted September 27, 2008 Share Posted September 27, 2008 Math Major eh? Link to comment Share on other sites More sharing options...
serge2k Posted September 27, 2008 Share Posted September 27, 2008 cool, yeah it's just two series and then a bit of algebra. Link to comment Share on other sites More sharing options...
believe_in_blue Posted September 27, 2008 Share Posted September 27, 2008 i hate to do this to you but in the first line of the work you posted above you assumed the result and that is why you get the right conclusion at the end. unfortunately this makes the proof invalid as stated. when you sum i^3 to k+1, you get (k+1)^3 + (the sum of i^3 up to k). your first line has stated that the sum of i^3 to k+1 = (k+1)^3 + (sum of i to k)^2. so in that line you've used the result you're trying to prove. i don't know if this is your entire proof, if so unfortunately you'll have to start again. if that's the case i can type something up if you still need some hints. Link to comment Share on other sites More sharing options...
serge2k Posted September 28, 2008 Share Posted September 28, 2008 i hate to do this to you but in the first line of the work you posted above you assumed the result and that is why you get the right conclusion at the end. unfortunately this makes the proof invalid as stated. when you sum i^3 to k+1, you get (k+1)^3 + (the sum of i^3 up to k). your first line has stated that the sum of i^3 to k+1 = (k+1)^3 + (sum of i to k)^2. so in that line you've used the result you're trying to prove. i don't know if this is your entire proof, if so unfortunately you'll have to start again. if that's the case i can type something up if you still need some hints. Link to comment Share on other sites More sharing options...
believe_in_blue Posted September 28, 2008 Share Posted September 28, 2008 ah okay i see what you did. i thought from your first proof you were trying to show the result using direct comparison, and that you accidently used the result as one of the steps in your comparison. proof by induction is definately the right way to do this problem... i should have realized that's what you were doing when i read your first proof but it's been a while since i've come across it. i'm confident the proof you just posted is complete, I didn't look at every algebraic step but I assume they are correct. Link to comment Share on other sites More sharing options...
serge2k Posted September 28, 2008 Share Posted September 28, 2008 they are. I realized that I hated series in calculus II and I still don't like them much now. I still have to my homework for that stupid probability/statistics course thats supposedly needed for 3rd year (comp sci) but 2 people are actually taking it (from 2nd year comp sci) Link to comment Share on other sites More sharing options...
WiLBoY Posted September 28, 2008 Share Posted September 28, 2008 they are. I realized that I hated series in calculus II and I still don't like them much now. I still have to my homework for that stupid probability/statistics course thats supposedly needed for 3rd year (comp sci) but 2 people are actually taking it (from 2nd year comp sci) Link to comment Share on other sites More sharing options...
serge2k Posted September 28, 2008 Share Posted September 28, 2008 Going into actuarial science? Link to comment Share on other sites More sharing options...
believe_in_blue Posted September 28, 2008 Share Posted September 28, 2008 they are. I realized that I hated series in calculus II and I still don't like them much now. I still have to my homework for that stupid probability/statistics course thats supposedly needed for 3rd year (comp sci) but 2 people are actually taking it (from 2nd year comp sci) Link to comment Share on other sites More sharing options...
believe_in_blue Posted September 28, 2008 Share Posted September 28, 2008 no, I don't even want to do the stats course but it's a prereq for the operating systems course that I'm taking next year. The problem I posted is actually from an algorithm analysis and design course. Link to comment Share on other sites More sharing options...
MillerGenuineDraft Posted September 28, 2008 Share Posted September 28, 2008 Does anyone know where the vikings are from? Link to comment Share on other sites More sharing options...
serge2k Posted September 28, 2008 Share Posted September 28, 2008 Minnesota. Link to comment Share on other sites More sharing options...
kanucks25 Posted September 28, 2008 Share Posted September 28, 2008 Does anyone know where the vikings are from? Link to comment Share on other sites More sharing options...
Ca.NucK10 Posted September 28, 2008 Share Posted September 28, 2008 Does anyone know where the vikings are from? Link to comment Share on other sites More sharing options...
Rypien37 Posted September 28, 2008 Share Posted September 28, 2008 Anyone wanna write a 5 page history essay for me? lol Link to comment Share on other sites More sharing options...
iheartluongo Posted September 28, 2008 Share Posted September 28, 2008 5 pages? lol.. my friend wrote a 99 page essay on world war 2 in grade 7. Link to comment Share on other sites More sharing options...
Ca.NucK10 Posted September 28, 2008 Share Posted September 28, 2008 5 pages? lol.. my friend wrote a 99 page essay on world war 2 in grade 7. Link to comment Share on other sites More sharing options...
Captain Bhangra Da Posted September 28, 2008 Share Posted September 28, 2008 who does homework on a saturday night Link to comment Share on other sites More sharing options...
Ca.NucK10 Posted September 28, 2008 Share Posted September 28, 2008 Essays? In grade 7? Wow. I actually love writing essays- when the topic is meaningful and interesting to me. Otherwise it's a pain in the donkey. Link to comment Share on other sites More sharing options...
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