Hello I downloaded an app that allows me to block google play, however I can still install apps through play.google.com via another device. Is there a way I can disable this? The app I'm using is called AppLock.
My mom has an android tablet and she doesn't even know what a site is, her e-mail, or even the password of her facebook account. She's an average user. The internet is facebook in her eyes. She has no need for apps or anything, it's just, only, precisely facebook. All is facebook.  How can I completely disable installing apps in android so they can't be installed in any way or form, I mean, not by URL, not by clicking, not by app store, not even by another program. Just disable the entire thing altogether.  Doesn't need to be safe, have locks, passwords etc. I'm not trying to secure the device from intruders, attackers or robbers, I'm trying to secure it from its very own user.  Please help. I just had to remove two anti-virus apps that were opening adware pages when she tried to open facebook lite, and that's obviously a no-go, apps which she "had not installed." Clearly there's some voodoo going on here for them to just popup, or maybe she just did it unknowingly, but none of that's relevant. How can you just disable installs so this couldn't ever happen again?
How can I prove that if $n$ is even then $n^2$ is even and if $n$ is odd then $n^2$ is odd? I'm using an unsigned repo in Ubuntu 16.04 from Debian multimedia:  deb http://www.deb-multimedia.org jessie main   To install deb-multimedia-keyring, I'm running:  apt-get update &amp;&amp; apt-get install deb-multimedia-keyring -y   This gives an error:  W: GPG error: http://www.deb-multimedia.org jessie InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5C808C2B65558117 E: The repository 'http://www.deb-multimedia.org jessie InRelease' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. Double vs. BigDecimal? Multiple solutions for a particle in an infinite potential well I am starting to learn about quantum mechanics and was wondering about the solutions to a question about a particle in an infinite potential well of length $L$.  The solutions are: $$\psi_n(x) = \sqrt{\frac{2}{L}}\sin\left(\frac{\pi n x}{L} \right)$$  And I was wondering what is the meaning of $n$. Isn't there supposed to be only one wave function? In that case, $\Psi = \sum_{n=1} ^\infty a_n \psi_n$, but what are the $a_n$? Or maybe it is probabilistic, and we don't know which $\psi_n$ the particle is currently in? the least possible value for :$ \lfloor \frac{a+b}{c}\rfloor +\lfloor \frac{b+c}{a} \rfloor+\lfloor \frac{c+a}{b} \rfloor $ How to install NVIDIA driver in Ubuntu I'm running Ubuntu 13.04 on DELL XPS L501 - Nvidia GeForce GT 420M. I'm using kernel 3.9.0-030900-generic.  All kernel-headers are installed in the system.  and  I've tried the following.   Use apt-get to install nvidia-current (which download 304) &amp;&amp; load using modprobe Use apt-get to install nvidia-310 &amp;&amp; load using modprobe Download nvidia 64-bit driver nvidia-319.23 for 400M series and install Use swat-x repo to install nvidia driver   All of these failed. And I tested it everytime like this   After the module is loaded (checked from lsmod),  restarted lightdm tested from get.webgl.org  (Google-Chrome webgl support is enabled)    Problem faced with nvidia-xconfig   after running nvidia-xconfig (which writes to /etc/X11/xorg.conf), and restarting lightdm, my display res changes to 640x480. and had to remove this file to revert back to old setting Have also tried commenting out those two lines which adjusts Horizontal and Vertical Setting in xorg.conf. That just rectified the resolution. But still I wasn't able to use the graphics card (webgl).   EDIT 1: (nouveau)   Tried rebooting after each installation Removed (purge) all of nouveau* before starting.  Removed one more package (dont remember the exact name though) - xorg-xserver-blah-blah.   EDIT 2: (bitlbee)   I had bitlbee installed before. Removed that too before starting installation. When bitlbee was present, NVIDIA-3.9-x86.run (downloaded from nvidia) was not able to recognize graphics card. But it did when I removed bitlbee. (So I'm assuming here that it should work if graphics driver was installed properly)   EDIT 3: (software-properties-gtk)   sudo software-properties-gtk the Additional drivers tab is always NIL. (before and after installation) (even if the installation was successful)   Have been trying this the whole day, and done it quite a few times. None of them worked.  Need help! Is it the problem with kernel-3.9, that there are no updates for this ? How can I make a macOS Mojave bootable USB installer in Windows 10? I have downloaded and saved macOS Mojave installation file from the Mac App Store into my external hard drive. Unfortunately, macOS has crashed on my Mac and now I need to install it again. I have used a software named TransMac to make a installation USB in windows following the steps in the link below:    But the provided USB drive after all these steps doesn't show up in my MacBook pro. Considering that I have saved Install macOS Mojave.app on my external hard drive, and I don't have access to any other Mac computers, How can I fix this issue and build a USB for installing Mojave? I used to do a full factory wipe then flashed a stock firmware with Odin, that helped me get back to having access to my mobile network then I flashed to Resurrection Remix 5.5.3 and lost access to my mobile network (Emergency Calls Only) I checked my IMEI and it appears to be valid. I didn't backup my /efs I didn't do anything to it. What seems to be the solution? I have a Samsung Galaxy S3 (I-9300) ImageView without xml definition Probability that a k digit number does not contain certain digits Ordering by the order of values in a SQL IN() clause What is the difference between a desktop environment and a window manager? I'm having a really hard time trying to understand what the differences between a desktop environment and a window manager are?  EDIT: From this :  There are basically three layers that can be included in the Linux desktop: X Windows – This is the foundation that allows for graphic elements to be drawn on the display.  builds the primitive framework that allows moving of windows, interactions with keyboard and mouse, and draws windows. This is required for any graphical desktop. Window Manager – The Window Manager is the piece of the puzzle that controls the placement and appearance of windows. Window Managers include: , , , , , etc. Requires X Windows but not a desktop environment. Desktop Environment – This is where it begins to get a little fuzzy for some. A Desktop Environment includes a Window Manager but builds upon it. The Desktop Environment typically is a far more fully integrated system than a Window Manager. Requires both X Windows and a Window Manager.  Examples of desktop environments are , , ,  among others) biblatex: Full Citations in Footnotes on Every Page How can I create this sort of bibliography using biblatex, ie, bibliography at the footer of every page? Survey database design: associate an answer to a user I'm doing the conceptual model for a survey database.  The goal is store the answers given by users (it's going to be an Android app).  I have three entities: user, question and option.  A question will have one or more options (for example: How many employees do you have? 1-40, 40-1000, +1000).  Options will have a text (1-40) and a value (the value selected by user).  User will select one (or more) of these options.  My conceptual design is:    I don't know how to associate an answer with an user.  How can I represent that relation? Do I have another entity to represent option value?  This model will store questions and pre-made answers (offered answers) and allows them to be re-used in different surveys.  I have to represent question like this one:    This question is related to this one: Let $A \in \mathbb{R}^{p \times p}$ and $B \in \mathbb{R}^{q \times q}$ be nonsymmetric positive definite matrices in the sense that $v^T A v &gt; 0, \forall v \in \mathbb{R}^p$ and $v^T B v &gt; 0, \forall v \in \mathbb{R}^q$.  I know that $A \oplus B$, i.e. a matrix with a block structure \begin{align} \pmatrix{A &amp; 0 \\          0 &amp; B} \end{align} is positive definite and I also know that if $p=q$, then $A+B$ is positive definite as well.  Can I say that as well if the blocks overlap partially? When?   For instance a matrix as follows: \begin{align} \pmatrix{a_{11} &amp; a_{12} &amp; a_{13} &amp; a_{14} &amp; 0&amp; 0\\          a_{21} &amp; a_{22} &amp; a_{23} &amp; a_{24}&amp; 0&amp; 0\\          a_{31} &amp; a_{32} &amp; a_{33} + b_{11} &amp; a_{34} + b_{12} &amp;b_{13}&amp;b_{14}\\          a_{41} &amp; a_{42} &amp; a_{43} + b_{21} &amp; a_{44} + b_{22} &amp;b_{23}&amp;b_{24}\\          0 &amp; 0 &amp; b_{31} &amp; b_{32} &amp;b_{33}&amp;b_{34} \\          0 &amp; 0 &amp; b_{41} &amp; b_{42} &amp;b_{43}&amp;b_{44}} \end{align} Copy current terminal prompt to clipboard Is there a way to copy the currently written content of the bash prompt? Say I wrote:  ping www.google.com   so that the lines in terminal looks like:  petr@sova:~$ ping www.google.com   and didn't hit return yet. I want to copy that text to clipboard. Is that possible?  The usual usecase would be hitting up several times and finding a command which I want to copy. QGIS3 - Clipping polygons to a hemisphere for azimuthal orthographic projection I'm a bit of a novice with QGIS, so this is really throwing me for a loop.  For the maps I'm intending on making, an azimuthal orthographic projection would be my preference.   For example, one map I'm trying to recreate is this map of the Pacific islands :    I've been using the NaturalEarth Quick Start package, which has been a really good launching-off point, but I'm running into some issues at the horizon of the orthographic projection.  I've tried adding a custom projection:  +proj=ortho +lat_0=0 +lon_0=170 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs   But that gives the following map:    Which certainly is close to being right, but the ocean is obviously being cut off in the Arctic and on the southern horizon.  I understand the issue is that naively mapping layers described in WGS 84 to an orthographic projection leaves you with artifacts at the horizon, but how do I fix it?    I first tried to use the Clip to Hemisphere plugin described in , but it seems incompatible with QGIS 3; when I try adding the plugin, QGIS3 gives an error message and places it in the "Invalid" section of the Plugins window.    I then tried both solutions presented at  Again the issue is with QGIS 2/3 incompatibility.    For Solution 1, both Numerical Digitize and CAD Tools are again incompatible with QGIS 3 and give the same result as Clip to Hemisphere.    For Solution 2, I can't disable on-the-fly-reprojection in settings since that setting was removed in QGIS 3. Arithmetic and geometric sequences: where does their name come from? Where does the name of these two famous types of sequences come from?  The article  of Wikipedia says that the geometric sequence is called like this because every term is the geometric mean of its two adjacent terms. Though it is true, it only reduces the question to: why is the geometric mean geometric (in opposition to the arithmetic mean).   Continuing my investigation on , I was told that a square with the same area than a rectangle with sides $a$ and $b$ has their geometric mean $\sqrt{ab}$ for side. That's again totally true, but a square with same perimeter than this rectangle of sides $a$ and $b$ has their arithmetic mean $\frac{a+b}{2}$ for side!  Thus, my question: Who coined these names? And why? Why is the geometric mean more geometric than the arithmetic mean? I would like to install the restricted extras package, which I didn't select during the install. How can I do that?        is a meta-package that installs:         Support for MP3 and unencrypted DVD playback   Microsoft TrueType core fonts   Flash plugin   codecs for common audio and video files I am working on a long document in LaTeX with documentclass book. I need the page number to always be in the upper right corner of each page, even if that page is the first page of a chapter (right now on 1st pages of chapters, the page number is bottom-centered, on all other pages it's top-right).  I control the position of the page number with fancyhdr:  \usepackage{fancyhdr} \pagestyle{fancy} \lhead{} \chead{} \rhead{\thepage} \lfoot{} \cfoot{} \rfoot{} \renewcommand{\headrulewidth}{0pt}   Also, I don't know if the problem is related but my chapters do not start from the top of the page. There is a white area, then comes chapter X, then a newline with the chapter line. What I also want is the chapter to start from the top of the page.  The main question here is how I can get the page number to always appear in the upper right corner, I mention the thing with the chapter title position only in case that might be related.