NationStates Jolt Archive

im desperate

http://forums.jolt.co.uk/showthread.php?t=466459

i was just wondering how to transform that into du/(u^2+1) so i can make it arctanu

Listen, Shqipes, you can't rely on us to do every little bit of homework for you. Read your notes and try things for yourself; it's by far and away the best way to learn how to do things. If you don't have answers to the questions you're given, go over a few examples in a textbook that do provide answers and try your best to manipulate your workings to fit the solutions. Doing that gives you an idea of a generally applicable method that you can understand and use, which is far more important than getting the questions right.

Listen, Shqipes, you can't rely on us to do every little bit of homework for you. Read your notes and try things for yourself; it's by far and away the best way to learn how to do things. If you don't have answers to the questions you're given, go over a few examples in a textbook that do provide answers and try your best to manipulate your workings to fit the solutions. Doing that gives you an idea of a generally applicable method that you can understand and use, which is far more important than getting the questions right.

its just that this is a very specific problem :(

i knew how to get up to here but i dont know how to incorporate this into arctanu:

http://i26.photobucket.com/albums/c144/slicknick727/integral.jpg

(if that 3 were a 1, it would be arctanu)

its just that this is a very specific problem :(

i knew how to get up to here but i dont know how to incorporate this into arctanu:

http://i26.photobucket.com/albums/c144/slicknick727/integral.jpg

(if that 3 were a 1, it would be arctanu)
This is all about how the result to arctan u works. It's about substitution.

Let u = (root 3) tan x

such that du/dx = (root 3) sec^2 x
and u^2 = 3 tan^2 x

So this gives us something of the form

Integral of { [ (root 3) sec^2 x dx ] / [ 3 ( tan^2 x + 1 ) ] }

One of our trig identities is

tan^2 x + 1 = sec^2 x

so by cancelling out terms, the integral becomes

Integral of { dx / (root 3) }

which is x / (root 3)

We then substitute back in for x to get

arctan (u / root 3) / root 3

And you can then apply limits as you see fit.


Again, though, the best way to approach this sort of thing when you see "Something that could be an Arctan" is to think about where your arctan term comes from and to derive something similar by the same principles. Something like this should have been available in your course textbook, and I'm sure had you thought about questioning where your idea of Arctan came from, you would have gotten there eventually.

Help you to spell please

im desperate

http://forums.jolt.co.uk/showthread.php?t=466459


Hang on, there is somebody who is actually paid to tell Shqipes this thing. If we step in here and 'help' him out we are essentially blacklegs.

arctanu

What is this? Scientology or summat?

Do your own damn homework.

It's one thing to come here and ask about one particular problem or because you need others opinions on something, but it's quite another to pester us with every single little thing.

I tell you what, if you want to integrate easily, buy Schaum's Mathematical Handbook, it has tables of integrals.

Hang on, there is somebody who is actually paid to tell Shqipes this thing. If we step in here and 'help' him out we are essentially blacklegs.
We're also potentially resulting in a greater earning for ourselves. If we do their homework, the teachers get paid but the kids don't learn anything. That way, they all suck once school is finished, thus eliminating the competition in the future job market. :D

We're also potentially resulting in a greater earning for ourselves. If we do their homework, the teachers get paid but the kids don't learn anything. That way, they all suck once school is finished, thus eliminating the competition in the future job market. :D
I thought of doing that once, but enforcing it on my friends and attempting to decieve all of the kids that study like its their job was hard. All in all, I just rely on my inherent sweetness to blow over the competition. :p

i wish i could not help people, it's kinda hard, especially if they're good looking girls. maybe i should start "charging" for help :p

We're also potentially resulting in a greater earning for ourselves. If we do their homework, the teachers get paid but the kids don't learn anything. That way, they all suck once school is finished, thus eliminating the competition in the future job market. :D

Naah, you are just helping him become a disenfranchised middle-manager, who doesn't know enough to do it himself, but can delegate. (but also never seems to get enough clout to get invited to the golf course with the big boys) The world needs lots of those.

its just that this is a very specific problem :(



As opposed to a vague, nebulous math problem?

"Discrete Math Midterm, Question #3:

Find some number with some number of digits that has some kind of property that includes some other property in some cases, but there're also some other things going on, too"

"Um...147863?"

"Sure, correct"

ooh maths! joy!!

*runs away very fast*

jumping Jesus on a pogo stick....

how did you get into school?

None of the problems you've posted so far are even remotely difficult - I'm quite sure your textbook explains the concepts for that sort of thing quite well.

If you can't do this basic stuff, you're never going on to anything more difficult - you have to be able to do calculus the same way you breathe air.

What country are you from?

He's American.

Here's what you do:

1) Locate course textbook.
2) Remove wrapping. This step is important.
3) Turn to relevant chapter.
4) ...

What country are you from?

We shouldn't ask him that, its just going to be depressing.

I'd help, but I'm not good at math myself.

Naah, you are just helping him become a disenfranchised middle-manager, who doesn't know enough to do it himself, but can delegate. (but also never seems to get enough clout to get invited to the golf course with the big boys) The world needs lots of those.
Hehe... That's that idea shot down. ^_^;