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420chan is Getting Overhauled - Changelog/Bug Report/Request Thread (Updated July 26)

I am fucked

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- Wed, 13 Aug 2014 17:08:21 EST YNH/O7Fa No.14283
File: 1407964101682.jpg -(26989B / 26.36KB, 417x407) Thumbnail displayed, click image for full size. I am fucked
So, I have a math placement exam coming up, and I am pretty sure I am fucked.
Though I did well in math during high school, it has been a few years since I graduated, and none of this is looking too familiar.
I am particularly having issues with finding domains. I have been trying to find practice problems similar to the ones I am working on now, but to no avail. I have an answer key to this practice test, but it doesn't explain shit. So, if someone could please explain domains in plain English, that would be great.

Here are some of the problems that appear on the practice test. I have simplified them, but I just don't understand at what point I am supposed to be finding the domain (before or after simplifying) and how to do that.

http://webalg.math.tamu.edu/ratlexp/sratl0301.pdf

Basically, I feel like a fucking idiot, so if anyone could help, I would be eternally grateful.
6 posts and 2 images omitted. Click View Thread to read.
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Ernest Honeywell - Tue, 19 Aug 2014 20:39:23 EST HLw3q9Du No.14292 Reply
>>14291
>it doesnt affect my power to mock fools who dont know basic mathematics
Why berate someone on a board about mathematics for understanding less math than you though? People come here for help. This isn't /b/. If you're coming here just to mock people who know less than you (and readily admit it), move the fuck along.
>>
Doris Chuvingwutch - Tue, 19 Aug 2014 21:49:43 EST Gw2IN3ba No.14293 Reply
1408499383788.jpg -(135861B / 132.68KB, 550x413) Thumbnail displayed, click image for full size.
So just to recap:

OP:
>I feel like a fucking idiot, so if anyone could help, I would be eternally grateful.

Anon:
>holy fuck this nigga doesnt know a domain from a denominator? go back to jr high dog
>>
Doctor Foster - Wed, 20 Aug 2014 05:23:39 EST BfGCwHN9 No.14294 Reply
1408526619196.jpg -(2203819B / 2.10MB, 3264x2448) Thumbnail displayed, click image for full size.
>>14293
www.coolmath.com Maybe this will help? SMH www.math4kids.com

Free Academic Courses Online

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- Fri, 25 Jul 2014 03:21:10 EST mSE/qEmh No.14247
File: 1406272870011.jpg -(27669B / 27.02KB, 593x457) Thumbnail displayed, click image for full size. Free Academic Courses Online
I know there are at least a couple websites that offer free courses, but the only one I can remember is edX.org, which offers more career-specific courses and I'm looking for general stuff. I just want to take math from the ground up, starting with elementary algebra. /math/ where can I learn algebra online?
2 posts omitted. Click View Thread to read.

A mathematical and artistic exercise: Higher Dimensional Beings

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- Thu, 10 Jul 2014 01:30:30 EST yGgK6aCs No.14192
File: 1404970230302.jpg -(83646B / 81.69KB, 463x720) Thumbnail displayed, click image for full size. A mathematical and artistic exercise: Higher Dimensional Beings
What I'm wondering is, what would it look like when a higher dimensional being moved through our dimensions? Obviously not a completely serious thread.
The artist/scientific portion of what I'm asking is: What would an intelligent life form look like in their n-dimensional glory?
The mathematical portion: I know you savages are capable of projecting n-dimensional structures into 3-dimensions. Has anything cool like this been done before? I'd be much more interested in projections with a time dimension.

The reason this interests me is that I'm fascinated with absolutely massive structures. The idea of a rapidly transforming organic structure popping in and out of existence is probably the most epic thing I can think of. The Halo games have been the most impressive things I've seen when it comes to showing you things with breathtaking scale. If the n-dimensional organic being was huge and a special effects company or game developer decided to take a swing at something like this, I'd be thrilled. I wouldn't mind you guys just talking about this instead of linking to media. I just don't hear this talked about very often.
12 posts and 1 images omitted. Click View Thread to read.
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Nell Drinningfuck - Sun, 10 Aug 2014 18:01:14 EST uspvjvJI No.14277 Reply
>>14273
>This video is not available in your country.

Did I just get teleported to China? WTF?
>>
Nicholas Grimgold - Mon, 11 Aug 2014 19:45:31 EST yGgK6aCs No.14278 Reply
1407800731014.jpg -(1376053B / 1.31MB, 4151x2749) Thumbnail displayed, click image for full size.
>>14273
That's exactly where I got the idea, actually. I was just wondering if you guys could get crazy on me. As a physics student, we regard you math guys as people who just do wild shit for no reason that nobody ever asks for. We pretty much assume that you could answer most questions we have but as I've framed my questions as more open, I don't expect too much. I will certainly be reading flat land and flatter land and hopefully smoke DMT at some point in the process. Right now both of my threads are the top threads. This is a terribly slow board isn't it, you hard working motherfuckers?
>>
Hugh Brarringville - Wed, 13 Aug 2014 13:50:05 EST Hs5ANTy/ No.14282 Reply
>>14278
I'm just repeating myself here, but read Diaspora. Flatland and its sequels are good but if you already have some math background they'll all cover some pretty obvious stuff.

There are tons of ways for life to exist in a world with three spacial dimensions, and even more in four or more, assuming physical laws which work in those spaces. Do you have any more specific questions or do you just want to be entertained?

If people in a four dinensional world had cars, their wheels could have two degrees of freedom and still be 'flat' on one side. Their roads would approxomate three dimensional tubes kr parallelpipeds and the wheels would touch the road as a flat 2d shape instead of a line. There would be no left or right side of the road, but the road would probably still just connect two points in something approximating a thin line as they do in our world. I could go on and on but after a point it's really pretty boring.

Quick nit picky thing about Epsilon Delta Limits

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- Fri, 08 Aug 2014 08:51:33 EST yGgK6aCs No.14271
File: 1407502293122.jpg -(16322B / 15.94KB, 300x319) Thumbnail displayed, click image for full size. Quick nit picky thing about Epsilon Delta Limits
I notice a few sources I've looked at specify that |x-a| is greater than 0, but never bother to do the same thing with |f(x)-L|. In my mind, if they do it with one and not the other, then I'm going to assume there is a reason for doing so and spend all sorts of time thinking about why the definition isn't symmetrical in this way. However, in my opinion specifying that the absolution value of anything is greater than zero seems completely redundant if we're beyond the discussion of what an absolute value is, so it seems to me that saying |x-a|< epsilon is complete. Is there a reason for specifying |x-a| is greater than zero or is this just a habit that's perpetuated?
5 posts omitted. Click View Thread to read.
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Eliza Dissleway - Tue, 12 Aug 2014 20:48:44 EST Gw2IN3ba No.14281 Reply
>>14280
This. It seems so obvious now you mentioned it.

Disregard my previous answer OP; apparently I didn't have my thinking cap on when I replied.
>>
driven !FTPgBqDDy. - Wed, 13 Aug 2014 21:57:16 EST y5R4M4OS No.14287 Reply
>>14271
That's because there's a difference between the definitions for the limit of a sequence and the limit of a function. I don't have my analysis textbook but in a couple of days I can expand on this

Also the first thing inside your absolute value sign should be something that changes with respect to something else (e.g. xn) because it doesn't make sense to be continually comparing fixed quantities. So i'll use xn to represent a sequence x1, x2, x3, ...

|xn-a| can be zero, it's just not very interesting and doesn't occur for things like xn = 1/n (a is a fixed quantity so it can't cancel with 1/n).
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Ernest Gengerfield - Mon, 25 Aug 2014 00:44:52 EST yGgK6aCs No.14308 Reply
1408941892614.jpg -(34803B / 33.99KB, 496x402) Thumbnail displayed, click image for full size.
>>14280

I totally get it now. We want to know the behavior around some point, disregarding what's actually happening at that point. However, we're perfectly fine with |f(x)-L| being zero. That's exactly where the asymmetry comes in. Thanks! No bump.

That background

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- Tue, 05 Aug 2014 17:26:04 EST y0c2N06s No.14265
File: 1407273964691.png -(1064430B / 1.02MB, 842x464) Thumbnail displayed, click image for full size. That background
How does one make an animation like here in the background?
https://www.youtube.com/watch?v=kJ6hGs4fRmA
>>
Ebenezer Peggleman - Tue, 05 Aug 2014 20:48:19 EST sPd/0oB/ No.14267 Reply
I'm the guy who advised you to post on /math/.
You need to learn how to code to at least make the gif/jpg/png.

Learn a simple language on which you can draw stuff, like Processing. Draw simple stuff first (bouncing ball), then move on more complicated pictures, like the Mandelbrot set or 2D Perlin Noise.
Draw a square grid, then draw an hexagonal grid, then draw rainbows all over it, then change the coordinates to polar to get a spiral.

https://www.youtube.com/watch?v=0ifChJ0nJfM
http://shadertoy.com/
https://processing.org/examples/noisewave.html
http://processing.org/examples/tree.html
https://processing.org/examples/mandelbrot.html
>>
Rebecca Blythehood - Tue, 05 Aug 2014 22:36:57 EST 4glIJRAX No.14268 Reply
1407292617680.jpg -(65630B / 64.09KB, 645x400) Thumbnail displayed, click image for full size.
Are BP oil spill jokes still relevant?

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