Stuck since I try to install dropbox
Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?
MapThread with non-rectangular lists The square roots of different primes are linearly independent over the field of rationals Prove that $\int_0^\infty \frac{x\,\log x}{(1+x^2)^2} = 0$ I have been asked to prove that $$\int_0^\infty \frac{x\,\log x}{(1+x^2)^2}\,dx = 0$$  I tried proceeding as follows: \begin{align} \int_0^\infty \frac{x\,\log x}{(1+x^2)^2}\,dx &amp;= \int_0^1 \frac{x\,\log x}{(1+x^2)^2}\,dx + \int_1^\infty \frac{x\,\log x}{(1+x^2)^2}\,dx \\ &amp; = \int_0^1 \frac{x\,\log x}{(1+x^2)^2}\,dx + \int_{u=1}^0 \frac{u\,\log u}{(1+u^2)^2}\,du\quad (\text{where }u=1/x) \\ &amp;= \int_0^1 \frac{x\,\log x}{(1+x^2)^2}\,dx - \int_0^1 \frac{u\,\log u}{(1+u^2)^2}\,du \\ &amp;=^? \int_0^1 0 \,dx \\ &amp;= 0 \end{align}  But I think that I should first show that the improper integral $\int_0^1 {x\,\log x}/{(1+x^2)^2}\,dx$ is convergent.  Do I need to show it? If yes, how to do so?  (I have been taught basic methods such as comparison, limit comparison and Dirichlet test.) Hidden features of Python Unable to open any graphical app with "sudo" Tried to find some answer here: , but it didn't solve my problem.  $ sudo gedit Failed to connect to Mir: Failed to connect to server socket: No such file or directory. Unable to init server: Could not connect: Connection refused.  (gedit:4574): Gtk-WARNING **: cannot open display:   only gedit in terminal works fine. This is my local computer, not a remote system. cant install or remove anything on 18.04 cause of DPKG error How do I grep for lines containing either of two words, but not both? I'm trying to use grep to show only lines containing either of the two words, if only one of them appears in the line, but not if they are in the same line.  So far I've tried  grep pattern1 | grep pattern2 | ... but didn't get the result I expected. How to create a table with long text and which packages use I had a problem with the laptop lid so I am using it with an external monitor. I was wondering if there is any way to power on the laptop without opening the lid, that is through ports.  Laptop: Dell Inspiron 1525 Construction of uncountably many non-isomorphic linear (total) orderings of natural numbers I would like to find a way to construct uncountably many non-isomorphic linear (total) orderings of natural numbers (as stated in the title).  I've already constructed two non-isomorphic total orderings. They are $$ 1 &lt; 2 &lt; 3 &lt;\ldots\\ 1 &gt; 2 &gt; 3 &gt;\ldots $$ where "$&lt;$" and "$&gt;$" are  strict total ordering relations.  Thanks in advance for your help. Sqlite3 by default sorts only by ascii letters. I tried to look in google, but the only thing I found were informations about collations. Sqlite3 has only NOCASE, RTRIM and BIARY collations. How to add support for a specific locale? (I'm using it in Rails application) It seems to me that we could change all the current spin values of particles by multiplying them by two. Then we could describe Bosons as even spin particles and Fermions as odd spin particles. Is there some consequence or reason why we can't simply change 1/2 as the smallest unit of spin into 1?  It just seems prettier this way. In fact, there's almost an interesting relation to even and odd functions in that if you switch any two bosons around the wave function stays the same while if you switch any two fermions around the wave function becomes negative. I want to run the command   python quast.py -o quast contigs.fasta   but I want to do this for multiple contigs.fasta files in multiple directories.  I'm running OSX. Finding the perimeter of a right triangle with area given How do I return the response from an asynchronous call? TikZ doesn't fill when node coordinates are used Can someone please explain me why the following code doesn't result in a fill?  And why, sometimes, I get such "very thin lines" artifact (that's visibile in my picture)?  \begin{tikzpicture} \node (A) at (0,0) {A}; \node (B) at (1,0) {B}; \node (C) at (1,1) {C}; \fill[red] (A) -- (B) -- (C) --cycle; \end{tikzpicture}   Here's what I get: How do question bookmarks work? What does bookmarking a question mean? How do you bookmark a question? Do users get updates on their bookmarked questions? Are my bookmarks publicly visible? How do you see your own bookmarks? How do you see other users' bookmarks? How do you see which users have bookmarked a particular question? What impact does the bookmark system have on the voting system? Can I &quot;un-bookmark&quot; a question? Can I search within my bookmarks? I've been reading an  ( eMagazine) relating to the Raspberry Pi; "An ARM GNU/Linux box for $25."  In the article, page 17 at the bottom it shows an area on the Pi where a track zigzags next to a straight one with the explanation text:     The “wiggles” in tracks, ensure signals are matched  electrically,   reducing interference and signal delay.  This is particularly   important for high speed video  data and HDMI signals.     I have very limited knowledge of electrical engineering so perhaps this is a very simple question but why would you incorporate these 'wiggles' in a PCB design?  I realise the quote gives me an answer and I sort of understand the interference point due to problems with power cables and coaxial cables running next to each other but I'd appreciate something assuming very little knowledge that explained why you would get the problems and how wiggles help. For example, why isn't the board covered in wiggles? Is there a way to merge to two bars in GNOME 3? Best case scenario would be to have one single bottom or top bar that has all the symbols on the left side and the rest like the time indicator, connections, on/off button, etc. on the right side.  Is that possible in any way? How do you debug through a compressed JavaScript file?