Ubuntu 14.04 won't let me login
Ubuntu gets stuck in a login loop
If $x_n \to 0$, show that $\sqrt{x_n} \to 0$ Let $x_n \geq 0$ for all $n \in N$. If $(x_n) \to 0$, show that $(\sqrt{x_n}) \to 0$  Unless I am missing something, this seems simple to me. Since $x_n$ converges for an arbitrary $\epsilon^2&gt;0$, we have $|x_n| &lt;\epsilon^2 $ for $n\geq N$. Taking square roots here we have $\sqrt{x_n}&lt;\epsilon$ for all $n\geq N$ which is what we needed to show. Is that all? If so, then why $x_n \geq 0$ is important? Prove that there exists such a set of $n$ positive integers Prove that for any positive integers $m$ and $n$ , there exists a set of $n$ consecutive positive integers each of which is divisible by a number of the form $d^m$, where $d$ is some positive integer not equal to $1$.  I don't know how to approach this question. how to extract multiple zipped and rar files recursively? I have a folder ExampleFolder which contains many zipped folders. These zipped folders also contains multiple zipped folders. How to go through ExampleFolder and extract all of its zipped folders recursively?   Note that ExampleFolder itself, is not zipped, it's just a normal folder  Okay now I know what's happening Rinzwind and nux answers are both correct (except that I have to keep pressing Y or A forever)  But it's seems that some of the zipped files, contained zipped files and rar files as well, the rar files will not be extracted by   while [ "`find . -type f -name '*.zip' | wc -l`" -gt 0 ]; do find -type f -name "*.zip" -exec unzip -- '{}' \; -exec rm -- '{}' \;; done    or whatever  Edit 2 Some files are named .r00 and r01, .r02 up to r14, they are rar files, but not .rar Using the same variable as a fixed and random effect in Mixed Effect Models Split a string by a delimiter in python Comparing two integers without any comparison Is it possible to find the greatest of two integers without any comparison? I found some  solutions:   if(!(a/b)) // if a is less than b then division result will be zero. {     cout &lt;&lt; " b is greater than a"; } else if (!(a-b)) // we know a is greater than or equal to b now.  check whether they are equal. {     cout &lt;&lt; "a and b are equal"; } else     cout &lt;&lt; "a is greater than b";   But if(c) or if(!c) is a comparison to zero. In addition it doesn't work for negative numbers. In fact I need a solution that avoids any if statement. Instead I should use switch statements and arithmetic operators. ThanX. What is the command to find out how much disk space is being used/remaining? Restore default apt repositories in sources.list from command line I am looking for the best method to restore /etc/apt/sources.list to default from the command line.  Is there no way to reference the source code of the package which generates this file or something like that? I want a trusted and version-independent way of restoring this file.  Solutions Ruled Out  Before you mark this as a duplicate, note that I have reviewed  already. It is only applicable if you have the Ubuntu GUI available. This question is specific to the command line.  I have also reviewed  where the accepted solution is someone pasted the contents of their sources.list file. This is not an appropriate way to restore the file as the intentions of the person providing the file contents cannot be verified and the file is subject to change with new releases.  I checked out the , but this is also not from Ubuntu so I do not plan to use it. Changed response to Recommendation questions now that there's a site for them? How to play blu ray .mkv files on ubuntu 20.04 LTS? How to play blu ray .mkv files on Linux? e.g:1080p.BluRay.DD5.1.x264-NTb.mkv I have this function:  $$ f(x,y) = \frac {xy}{|x|+|y|} $$  And I want to evaluate it's limit when $$ (x,y) \to (0,0)$$ My guess is that it tends to zero. So, by definition, if:  $$ \forall \varepsilon \gt 0, \exists \delta \gt 0 \diagup \\ 0\lt||(x,y)||\lt \delta , \left|\frac{xy}{|x|+|y|}\right| \lt \varepsilon $$ Then $$ \lim_{(x,y)\to(0,0)}\frac {xy}{|x|+|y|} = 0 $$ So:  $$ \left|\frac{xy}{|x|+|y|}\right| = \frac{|xy|}{|x|+|y|} = \frac{|x||y|}{|x|+|y|} \le 1 |y| \lt \delta $$  So for any $$\delta \lt \varepsilon$$ the inequality is true. Hence, the limit exists and is equal to zero.  . Am I wrong or is Wolfram|Alpha wrong? Death in SAO before Kayaba announcement I was wondering if in the novel we knew about some deaths occurring before Kayaba announcement. I remember that in the anime, Kirito plays a bit with Cline before realizing that the log off option has disappeared. Then all the people are summoned to the city and learn about the fact that if they die in the game, they also die in real life.  I don't remember any players dying before the announcement in the anime, except for those who are not waking up and their relative pulling off their NerveGear thus causing death, but maybe in the light novel, some guys died without even knowing it just while being defeated by a mob (which seems awful for me).  Do we know about some players dying before that while thinking they are still in a normal game? I've read some great on-topic example questions on Area 51.  My questions:   Should a proposed site's "Great On-Topic Example" questions be automatically included in its beta? Will a proposed site's "Great On-Topic Example" questions be automatically included in its beta? Using a foreign driver's license in California when staying with a J-1 visa I'm planning to attend a Californian university as a visiting scholar (not paid by the university) on a J-1 visa, for a total of four weeks; a colleague of mine will do the same, but for 12 weeks. I've been told (personally, ie. no citable sources) that, if you're staying on a J-1, you're effectively a California resident for the time you're there, and, therefore, need a Californian driver's license.  I've read up on this and found  that states:     If you are a visitor in California over 18 and have a valid driver   license from your home state or country, you may drive in this state   without getting a California driver license as long as your home state   license remains valid.      If you become a California resident, you must get a California driver   license within 10 days. Residency is established by voting in a   California election, paying resident tuition, filing for a homeowner's   property tax exemption, or any other privilege or benefit not   ordinarily extended to nonresidents.   I'm not planning to vote in any elections, nor will I own a home there, but I'm not sure what would constitute "privileges or benefits not ordinarily extended to nonresidents".  Do we need to get driver's licenses in California, or can we use our foreign licenses? How about day trips to Arizona or Nevada?  Note: this seems to be related to , but my question is specifically about staying there on a J-1. This dreaded issue started at some time after upgrade to OS X (Yosemite) 10.10.3. accountsd uses about 60% CPU constantly, making the laptop hot and noisy.  I'm not using iCloud at all.  Killing it doesn't help, because it starts again quickly.  Probably related question, but it's about iOS: Can you run Android in a VM on PC? I came across a how-to guide for running Android 1.7 in a virtual machine (VirtualBox), but 1.7 is old. I haven't been able to find a Android 2.2 or 2.3 image anywhere, does anyone have any ideas on how to virtualize newer Android OS's? Preferably a free virtualization solution like VirtualBox.  Here is the link about virtualizing 1.7:    They send you to here to download Android disk images:    But I can't find anything newer than 1.7, anyone have any ideas? "Friendly" terminal color names in shell scripts? I'm aware of libraries in languages such as Ruby and Javascript to make colorizing your terminal scripts easier by using color names like "red".  But is there something like this for shell scripts in Bash, or Ksh, or whatever? After installing the latest Ubuntu I find that the icons in the applications folder (viz. /usr/share/applications), when opened in the Files application (Nautilus), come up as a blank page with a gear in the middle. If I try to open them I get a read only text box. So, my friend just implemented a bunch of new mods into his SMP server, which meant a host of new commands to play with.  I thought I'd give the /mobspawn command a few goes, and see what I could achieve.  So I headed off to the server's jail (I forget why this particular location compelled me), and gave it a few spins.    I seem to have made a bit of an error in judgement.     What can I do to get rid of this mess?  Is there a command or some other technique I can use to clear out any mobs in my immediate vicinity? I have got a template class as follows:  class MyClass&lt;T&gt; {     T field;     public void myMethod()     {        field = new T(); // gives compiler error     } }   How do I create a new instance of T in my class?