Saturday, March 22, 2008
Area and Volume 5a/3b
Anyone know how to do any of these problems? On 3b I end up with pi(lnx)^2, and I can't integrate it. Does anyone know how to integrate it without a calculator or is my equation wrong? I have a similar problem on 5a; I can integrate the cos x in my equation but not ln(x^2+1). Scientific calculators are allowed but I don't see how they help. Anyone know what to do?
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5 comments:
Yeah, I can't integrate for 3b either.
Actually, I think I know how to integrate 3b! I was on Google and I found two websites that explain how to integrate it and they end up with "xln^2(x) - 2xlnx + 2x" as the answer. Here's the links for the two websites if you want them.. I hope they're right! hahah sorry if they arent!
http://www.karakas-online.de/forum/viewtopic.php?t=4026
and
http://answers.yahoo.com/question/index?qid=20070417142048AAWzfUK
(lnx)^2 can be integrated using the substitution by parts (with uv-"integral"vdu), where one of the lnx's is u, and the other is dv! I think it comes to what maria found! :)
Yeah, I integrated using integration by parts. It works out to your answer Maria. I do not know how to do 5a either. Someone help please!
for 5a i think you are suppose to use the calculator because otherwise you can't find the intersection points. there is a dollar sign in front of the problem maybe she meant to put a asterisk.
if you use the calculator you'll get the intersection points to be +/- 0.91586 then you can look at the graph to find the eqution for the integral.
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