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View Full Version : Integration problem, wolfram stumped!



cause
03-07-2012, 03:22 AM
Hey guys, I'm working on this question:

http://puu.sh/jLfy

Wolfram gives me this:

http://puu.sh/jLcX

So I'm kinda stumped (yes I lean on wolfram).
I can't see anything in my Reference pages that would be of help, any ideas?

Brandon
03-07-2012, 03:34 AM
Anything to the -1 u bring down on the bottom..

X ^ -n = 1 / (X^n)

tan ^-1 (x) = 1 / tan(x) * the x^2 that's already downt here..

cause
03-07-2012, 03:44 AM
Yesh, I get that part :P, it's the integral to follow which has me wondering.

Methrend
03-07-2012, 03:51 AM
I know that there's a fair amount of textbooks that use Tan^-1 to represent ArcTan.
Try putting it into Wolfram as ArcTan instead
http://www.wolframalpha.com/input/?i=integral%28%28ArcTan%29%2F%28x%5E2%29%29

cause
03-07-2012, 03:53 AM
Thanks so much!

the flea
03-07-2012, 04:57 PM
your not inputting the correct equation tan-1(x) is not equal to 1/tan(x)

tan-1(x) is the same as atan(x) or arctan(x). For some reason only americans use atan and arctan the rest of the world use tan-1 to represent this.

http://i40.tinypic.com/2dinfoy.png

Also for learning purposes wolfram is not very good IMO. I have been told that it can get things wrong due to it messing up with its logic which will in turn make you learn it wrong. I recommend you look up a program called MathCAD 15, its much more powerful and easier to use.