here is result  when I typed Can anyone solve my problem? after doing execute command of following   install libavcodec-extra   I realized that vlc and golden dict disappeared.  some other apps may also be affected by the command but so far i have confirmed were the two.  I executed command sudo apt-get autoremove that removed some files.  but still I am not able to restore my vlc and golden dict.  apt-get install vlc Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  vlc : Depends: vlc-nox (= 2.1.2-2build2) but it is not going to be installed        Depends: libvlccore7 (&gt;= 2.1.0) but it is not going to be installed        Recommends: vlc-plugin-notify (= 2.1.2-2build2) but it is not going to be installed        Recommends: vlc-plugin-pulse (= 2.1.2-2build2) but it is not going to be installed E: Unable to correct problems, you have held broken packages.       When I do apt-get update I will get error of PUBLIC KEY  W: GPG error: http://archive.ubuntu.com trusty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal?
This is a homework problem and I'm having trouble just getting a basic understanding.  I understand that $S_6$ is a symmetric group of degree $6$.  I'm not sure how to start looking for elements. How is voltage always able to increase, if electrons move at the speed of light? Suppose I installed ubuntu with the user usr1 then I added usr2. I then create a group grp1 where this 2 users are added. A folder is owned by usr1 and has group grp1. But when I login as usr2 I cannot write. The folder has permissions 755...  usr2@kmserver:/media/data/www$ groups usr1 usr1 : grp1 ... usr2@kmserver:/media/data/www$ groups usr2 usr2 : grp1 ... usr2@kmserver:/media/data$ ls -l total 20 drwx------ 2 root root 16384 2011-05-12 10:53 lost+found drwxrwxr-x 2 grp1   grp1    4096 2011-05-12 15:15 www   Whats wrong? What point (pt) font size are \Large etc.? In the preamble I have:  \documentclass[a4paper,11pt]{article} \usepackage{fontspec} \setmainfont{Arial}   What can be inferred about the real font pt size for the following?  \tiny, \scriptsize, \footnotesize, \small, \normalsize, \large, \Large, \LARGE, \huge, \Huge I was watching this  on making a custom UI tab using Python, and in the line from bpy.types import Menu, Panel, UIList, I see the names of objects that look like they can all be used to make different UI elements. Does bpy.types contain all the objects that people use when they want to make custom UI elements? What's the right way to represent phone numbers? Continuous bijection from $(0,1)$ to $[0,1]$ Does there exist a continuous bijection from $(0,1)$ to $[0,1]$? Of course the map should not be a proper map. Minimum value of $\left(a+\frac{1}{b}\right)^2+\left(b+\frac{1}{c}\right)^2+\left(c+\frac{1}{a}\right)^2$ Given $a,b,c \in \mathbb{R^+}$ such that $a+b+c=12$   Find Minimum value of $$S=\left(a+\frac{1}{b}\right)^2+\left(b+\frac{1}{c}\right)^2+\left(c+\frac{1}{a}\right)^2$$  My Try: By Cauchy Schwarz Inequality we have  $$\left(a+\frac{1}{b}\right)+\left(b+\frac{1}{c}\right)+\left(c+\frac{1}{a}\right)\le \sqrt{3}\sqrt{S}$$  $\implies$  $$\sqrt{3S} \ge 12+\frac{1}{a}+\frac{1}{b}+\frac{1}{c}$$  Now by $AM \ge HM $ inequality we have  $$\frac{a+b+c}{3} \ge \frac{3}{\frac{1}{a}+\frac{1}{b}+\frac{1}{c}}$$ $\implies$  $$\frac{1}{a}+\frac{1}{b}+\frac{1}{c} \ge \frac{3}{4}$$  hence  $$\sqrt{3S} \ge 12+\frac{3}{4}=\frac{51}{4}$$  hence  $$3S \ge \frac{2601}{16}$$  so $$S \ge \frac{867}{16}$$  is this approach correct and any better approach please share. Dihedral group - elements of order $2$ If $D_{n}$ is the Dihedral group of degree $n$ (order $2n$) where n is an odd number, can I then conclude that the numbers of elements of order 2 in $D_{n}$ is equal $n?$  I suppose there are the following types of elements in $D_{n}$: b, $a^{i}$, $a^{i}b$ for some $0\leq i &lt; n$ . What's the difference between "cardinal" and "ordinal" as adjectives? Whether and how to thank a girlfriend or boyfriend in the acknowledgements of thesis? What's the difference between stochastic and random? How secure is Activation Lock on iOS 7 (and later)? Showing that $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$ contains multiplicative inverses Why must $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$ -- the set of all polynomials in $\sqrt{2}$ and $\sqrt{3}$ with rational coefficients  -- contain multiplicative inverses?   I have gathered that every element of $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$ takes form $a + b\sqrt{2} + c\sqrt{3} + d\sqrt{2}\sqrt{3}$ for some $a,b,c,d \in \mathbb{Q}$, and I have shown that $\mathbb{Q}[\sqrt{2}]$ and $\mathbb{Q}[\sqrt{3}]$ are both fields, but it's not clear to me why this allows for general multiplicative inverses to exist in $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$. View the change history of a file using Git versioning How can I view the change history of an individual file in Git, complete details with what has changed?  I have got as far as:   git log -- [filename]   which shows me the commit history of the file, but how do I get at the content of each of the file changes?  I'm trying to make the transition from MS SourceSafe and that used to be a simple right-click → show history. $X$ is a topological space with no special properties.  If a space $X$ has no isolated points, then show the same for any dense subset of   $X$.  Thanks a lot. Embedded quotes in arcpy.CalculateField_management expression I'm using arcpy.CalculateField_management to populate a field.  The expression:  "'https://anystate.gov/someportal/DisplayQueryResults.aspx?Prompts=Spill%20Number="!ID!"&amp;Database=OfficeDocs&amp;Query=DEP_Spill_Projects&amp;QuerySet=Portal_Queries&amp;User=Portal.DEP&amp;Password=DEPPortal1'"   will work when entered into the Calculate Field Tool.  The url is completed by pulling in values from the ID field.  However, the Python code snippet pasted into my script results in a syntax error. It's worth noting the expression is bounded by """"'....'"""" (4 double quotes outside a single quote.  I tried Midavalo's suggestion a couple of different ways. First attempt set  expression = 'https://anystate.gov/someserver/…{0}&amp;Database=OfficeDocs&amp;Query=DEP_Sp‌​ill_Projects&amp;QuerySe‌​t=Portal_Queries&amp;Use‌​r=Portal.DEP&amp;Passwor‌​d=DEPPortal1'.format‌​(!ID!)   Resulting in invalid syntax  Based on the Python link, the second try included single quotes:   'https://....'.format('!ID!')    But the result was a syntax error How do I test a private function or a class that has private methods, fields or inner classes? How do I unit test (using xUnit) a class that has internal private methods, fields or nested classes? Or a function that is made private by having  (static in C/C++) or is in a private () namespace?  It seems bad to change the access modifier for a method or function just to be able to run a test. While moving custom profiles using eclipse from dev org to partner org found following errors How do I set up Ruby on Rails? I am interested in setting up a Ruby on Rails environment on my 10.10 laptop.   Is there anything special I need to keep in mind for installation (i.e. that could be new or unique to 10.10)?   Are there any suggested walkthroughs that I could follow along with?  Thanks in advance.