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Calculus Help

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.undetected
Posts: 1076 - Karma: -445
Every time I try to find a video that explains indefinite integration of natural logarithms, it always uses u substitution. Does anyone know where I could find a video explaining another way to do so, without u sub. I can't seem to find any.
Mar 18 2014 8:02PM
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The_Polock
Posts: 345 - Karma: 1,280
Fuck I didn't know there was another way to do it. All I remember is the brown calc method and it used udu substitution...good luck. Honestly I am glad I am done with that shit. Never have used it damn it!
Mar 18 2014 8:15PM
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.undetected
Posts: 1076 - Karma: -445
My teacher showed us another way to do it, but I forgot the name of the method, it was easier than u sub, but apparently nobody uses it because it isnt on youtube at all. Which may mean my teacher was lying
Mar 18 2014 8:17PM
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Bombogenesis
Posts: 1984 - Karma: 4,006
I assume your teacher is specifying that you need another method? I'd try to help but idk what to even search. I learned usub and I assumed that was it.
Mar 18 2014 8:18PM
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Anathema
Posts: 21048 - Karma: 5,061
the answer is in the arctan
Mar 18 2014 8:19PM
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ChillTeenDad420
Posts: 1858 - Karma: 5,512
Mar 18 2014 8:38PM
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MilaKunis
Posts: 1480 - Karma: 3,646
OP is it the dy/dx method?
Mar 18 2014 8:41PM
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DasGoatenshafter
Posts: 580 - Karma: 307
The only methods of integration I've used up until my final calc course are u sub and integration by parts... or wolfram alpha
Mar 18 2014 8:44PM
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FerrisBueller
Posts: 8280 - Karma: 5,173
you can take the integral of lnx without udu sub watch the kahn academy
Mar 18 2014 8:45PM
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.undetected
Posts: 1076 - Karma: -445
Yea I think that is it
Mar 18 2014 9:11PM
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That_One_Dude
Posts: 1050 - Karma: 760
The only other common method for a log or natural log I can think of is integration by parts. That is where you use the equation integral(U*dv)=U*V-integral(V*du).
Mar 18 2014 9:41PM
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Puzzled
Posts: 4267 - Karma: 4,448
amen
Mar 18 2014 9:42PM
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chickenonabun
Posts: 461 - Karma: 285
you can do this one with integration by parts, I remember doing it that way a few months ago but I forgot how I did it. It was something with setting one of the parts dx to = dv or du...
Mar 18 2014 9:49PM
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msg
Posts: 1108 - Karma: 3,269
integration by parts brutha. khan academy it, sal is a godsend
Mar 19 2014 9:41AM
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John18_6
Posts: 7313 - Karma: 49,163
http://integral-table.com/downloads/single-page-integral-table.pdf
Mar 19 2014 10:18AM
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airplaneface
Posts: 219 - Karma: 685
int (ln(ax) dx) The integral of ln(ax)
u=ln(ax) dv=dx Set U equal to ln(ax) and dv equal to dx
du= (a/x) dx v=x Derive u and integrate dv to get du and v
int (ln(ax) dx) = uv - int (v du) Equation for integration by parts
int (ln(ax) dx) = (ln(ax)) * x - int( x * (a/x) dx) Sub u, v and du into the equation


==x * ln(ax) - x + C Solve

Mar 19 2014 11:10AM
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Heart
Posts: 6156 - Karma: 3,462
Yuck, I hated dong integration by parts and u substitutions. Just know that if you end up moving on to higher level math you will never have to do that kind of stuff by hand. Maple will be your savior.
Mar 19 2014 12:56PM
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chicken
Posts: 6843 - Karma: 2,123
really?

I have to do that often still. although I never actually write down what u is or what f & g are, I just kinda do it all in one step. I guess it depends on what type of higher level math you are doing?
Mar 19 2014 2:05PM
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Heart
Posts: 6156 - Karma: 3,462
I'm doing engineering so we generally don't do much of our calculation by hand
Mar 19 2014 3:22PM
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CliffyByro
Posts: 5678 - Karma: 3,903
i skimmed the thread so i dunno if someone answered you but are you asking because you need another method or just because you want another one? because its really simple once you crack it and you'll be able to do loads of different integrations without even thinking about them. i think someone posted the khan academy video, which is great. they basically taught me the most recent maths course i did this year at university
Mar 19 2014 3:54PM
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matoco
Posts: 35 - Karma: 69
If your not doing u-sub's you need to to integration by parts. I remember it by saying ultraviolet voodoo.

integral of (u*dv)= u*v-integral of (v*du)
Mar 19 2014 5:52PM
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matoco
Posts: 35 - Karma: 69
I just posted that without really remembering how to do it. But here it can walk you through:

u=ln(x)
dv= dx

v= x
du=1/x dx

integral(u dv) = u*v -integral (v*du)

=ln(x)*x-integral(x*1/x*dx)
=ln(x)*x-integral(dx)

=x*(ln(x)-1)
Mar 19 2014 5:59PM
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Bombogenesis
Posts: 1984 - Karma: 4,006
I'm so glad I'm done with this stuff. What a nightmare
Mar 19 2014 9:53PM
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radmad
Posts: 91 - Karma: 194
integration by parts literally sucks, especially when you have to use it like six times on a test. smh. calcudie.
Mar 19 2014 10:05PM
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chicken
Posts: 6843 - Karma: 2,123
integration by parts is a nightmare? you suck.
Mar 19 2014 10:48PM
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radmad
Posts: 91 - Karma: 194
calculus was invented by satan and you know it
Mar 19 2014 11:16PM
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DrZoidberg
Posts: 5675 - Karma: 4,268
You mean invented by humans to conquer satan and god at the same time? Sounds right to me.
Mar 19 2014 11:18PM
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radmad
Posts: 91 - Karma: 194
improper integrals make my head hurt….
Mar 19 2014 11:22PM
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chicken
Posts: 6843 - Karma: 2,123
well if you want to understand anything about nature you gotta learn that shit. and differential equations. and linear algebra. and complex analysis. maybe at least a little algebra and geometry as well.
Mar 20 2014 12:03AM
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radmad
Posts: 91 - Karma: 194
my head hurts
Mar 20 2014 12:04AM
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DIPED_IN_SAUCE
Posts: 858 - Karma: 2,256
y=mx+b
x=(-b+- sqrt(b^2-4ac))/2a
soh-cah-toa
tan= cos/sin
hope this helps
Mar 20 2014 12:25AM
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chicken
Posts: 6843 - Karma: 2,123
Click for larger image
Mar 20 2014 1:31AM
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ski.cats
Posts: 577 - Karma: 352
avoiding u sub in integration is like avoiding the chain rule in differentiation
Mar 20 2014 2:59AM
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Bombogenesis
Posts: 1984 - Karma: 4,006
Sorry, when I was in college I spent my time doing other things than nerding out over calculus and making troll threads about veganism on ns.


Who sucks now?
Mar 20 2014 9:11AM
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chicken
Posts: 6843 - Karma: 2,123
first year uni I went skiing every week, partied at least three nights a week and did not attend class at all.

you still suck.
Mar 20 2014 6:03PM
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Heart
Posts: 6156 - Karma: 3,462
But did you adhere to a strict vegan lifestyle and make bad troll threads about it on NS?
Mar 20 2014 7:15PM
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TNORTS
Posts: 2076 - Karma: 2,754
I consider myself terrible at math. Like really bad. I got C's and D's in it all through highschool. Integration by parts is easy.
Mar 20 2014 8:24PM
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FuckAllOfYou
Posts: 3864 - Karma: 2,518
SICK BRO!!!!!
Mar 20 2014 8:33PM
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Bombogenesis
Posts: 1984 - Karma: 4,006
Then second year at uni you moved to spray painting McDonald's signs with your douchebag friends and then begging mods to delete the thread you made about it cause you got scared?


Haaaaaaaaaaaaaaaaaaaaaa
Mar 20 2014 10:21PM
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DIPED_IN_SAUCE
Posts: 858 - Karma: 2,256
cotan*
Mar 21 2014 12:17AM
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chicken
Posts: 6843 - Karma: 2,123
nope. second year I was still skiing and partying a ton. face it. you are just an idot. what major are you? probably fucking business or something stupid haha.
Mar 21 2014 4:37AM
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Bombogenesis
Posts: 1984 - Karma: 4,006
Majored in idot minored in finding your moms g spot
Mar 21 2014 5:44AM
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msg
Posts: 1108 - Karma: 3,269
honestly you guys point out chickens attempts to piss you off but then you fall for his shit time and time again it's classic
Mar 21 2014 7:39AM
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.undetected
Posts: 1076 - Karma: -445
ayylmao
Mar 21 2014 9:05AM
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oil.
Posts: 2255 - Karma: 1,254
dude, you've been a member for like, 5 months...
Mar 21 2014 9:55AM
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airplaneface
Posts: 219 - Karma: 685
Man, what liberal arts school did you go to that they have those as degrees?
Mar 21 2014 10:16AM
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Bombogenesis
Posts: 1984 - Karma: 4,006
Chicken Shit University
Mar 21 2014 2:28PM
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msg
Posts: 1108 - Karma: 3,269
and in that time i've seen people get cranky multiple times

oh and i forgot how people can't look at the forums without an account..o wait
Mar 21 2014 6:31PM
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