I have a dual boot system in my laptop (windows 8 and ubuntu). I have decided to delete ubuntu and only use windows 8 in the system (I'm planning only to use ubuntu from usb boot). I tried to delete ubuntu partition from windows 8 and it wasn't ended up pretty good, I couldn't boot up to my windows 8 anymore. I've found that I need to uninstall GRUB first. I also found that I'll need a windows 8 recovery disk or bootable usb  to uninstalling GRUB but the problem is I can't boot up to my windows 8 bootable usb either (and I don't have any luck using recovery disk, mine is broken). How do I uninstalling GRUB then? Please help.
I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.
Can mobs go through doors? I was wondering if mobs can go through doors or not. It's the difference between me just putting up a door to my house, or putting up dirt instead. Footnotes in tables? How can I create a new extensible symbol? Given an arbitrary thin vertical symbol, can I create a new math delimiter from it (and if so, how)?   Edit: Ideally, I would like to be able to create an extensible symbol, either built out an existing normal symbol, or even made from scratch.  Edit 2: I am pretty sure that what I am after is an explanation of how to create a .tfm file for an extensible symbol (which Werner's answer describes the general structure of, but not how to make one).    For example, let's say I wanted to use the \dagger () or \wr () symbol as a delimiter, and write expressions like    \[\left\ldagger \sum_{n=1}^\infty a_n \right\rdagger\]   where the symbol scaled appropriately. Would there be any distinction between declaring a symmetric delimiter (like \vert), as opposed to one that has inherently different "left" and "right" versions like [ and ]?  Now, even being unaware of the inner workings of TeX, I imagine that there has to be lots of information in the fonts for how a delimiter is to be scaled in different situations, and if I try to make my own delimiter, this information won't be present. Would I need to get deep into FontForge or equivalent to achieve my custom delimiters, or is there an easier way? How critical are macOS Mojave compatibility requirements? As per Apple support document, :     1. Check compatibility      You can upgrade to macOS Mojave from OS X Mountain Lion or later on   any of the following Mac models. Your Mac also needs at least 2GB of   memory and 12.5GB of available storage space, or up to 18.5GB of   storage space when upgrading from OS X Yosemite or earlier.         MacBook introduced in early 2015 or later   MacBook Air introduced in mid 2012 or later   MacBook Pro introduced in mid 2012 or later   Mac mini introduced in late 2012 or later   iMac introduced in late 2012 or later   iMac Pro (all models)   Mac Pro introduced in late 2013, plus mid-2010 or mid-2012 models with a recommended Metal-capable graphics card.      I am currently running macOS High Sierra on my Early 2011 MacBook Pro.  What does Apple's requirements mean for my ability to install Mojave? Is it possible or worthwhile to do so? How do I transfer data and settings from one Apple Watch to another? I have an Apple Watch. I have had it for a while. I just bought a new Apple Watch. (Both are Series 1, just different sizes.)  I would like to transfer all my data and settings from my old Apple Watch to my new Apple Watch and then sell my old Apple Watch.  Is it possible to migrate my profile from one Apple Watch to another?  If so, what is the procedure?  All the search results I have found have to do with moving an Apple Watch to a new iPhone or restoring a backup to the same Apple Watch. Perhaps it is possible to restore a backup from an old Apple Watch onto a new one? I'm trying to downgrade my iPhone from the current iOS to an older one, as per .  But every time I try, I always receive this error:     The iPhone could not be restored. This device isn't eligible for the requested build.     I have tried many times with and without DFU mode. Any ideas regarding this? Use the triangle inequality to show that $|a|+|b| \leq |a+b|+|a-b|$ How would I go about proving that  $$|a|+|b| \leq |a+b|+|a-b|$$  Using the triangle inequality?  I tried squaring both sides, yielding:  $$|a|^2 +|b|^2 +2|a||b| \leq 2|a|^2+2|b|^2+2||a|^2-|b|^2|$$  Is it correct to move the terms to the other side? I tried $$2|a||b| \leq |a|^2+|b|^2+2||a|^2-|b|^2|$$ Then it is obvious that  $$0\leq |a|^2+|b|^2-2|a||b| +2||a|^2-|b|^2|$$ $$0\leq (|a|-|b|)^2 +2||a|^2-|b|^2|$$ $$0\leq ||a|-|b||^2 +2||a|^2-|b|^2|$$  But I have neither used the triangle inequality, nor it looks mathematically rigorous for my real analysis class. Any tips and tricks for solving these problems? Complex number identity by trigonometry Show that $\lvert e^{i\theta} - 1\rvert = 2\lvert\sin(\theta/2)\rvert$ by using the geometry of the triangle with vertices 0, 1, and the midpoint of the line joining 0 and $e^{i\theta}$.  I have been able to show this identity through other means, however I am stuck on how to utilize this particular triangle. Is it ok to say 'sorry' where you otherwise would use 'excuse me'?  Example: "Sorry, but could you show me the way to the next train station?" S. Weinberg, “The Quantum theory of fields: Foundations” (1995), Eq. (9.2.15) In Weinberg's book The Quantum Theory of Fields, Volume 1 on p.388 (Chapter 9), the following identity is used (with $f$ being any "reasonable" function):  $$f(+\infty) + f(-\infty) = \lim_{\epsilon \rightarrow 0^+} \epsilon \int_{-\infty}^{+\infty} d\tau f(\tau) e^{-\epsilon |\tau|}.\tag{9.2.15} $$  I don't understand the identity in a qualitative / heuristic way. Two very closely related questions:  If a card has two different "Sacrifice this creature for X" abilities on it, does sacrificing it give both benefits?  Likewise, if a card requires a creature to be sacrificed, but that creature has a "Sacrifice this creature for X" ability, do you get the sacrifice benefit when you sacrifice it for the other requirement? How do I make an HTML text box show a hint when empty? "More clear" vs "Clearer": when to use "more" instead of "-er"? How can I change the date and time on Ubuntu? Windows Active Directory naming best practices? This is a  about Active Directory domain naming.   After experimenting with Windows domains and domain controllers in a virtual environment, I've realized that having an active directory domain named identically to a DNS domain is bad idea (Meaning that having example.com as an Active Directory name is no good when we have the example.com domain name registered for use as our website).   , but I'm still not sure about what other rules there are around naming Active Directory domains.  Are there any best practices on what an Active Directory name should or shouldn't be? How to move from screen 1 to screen 3 by moving cursor to the left and vice versa? If I have to move the mouse from the left screen all the way to the right screen, the distance is quite big.   Is there a way to virtually connect the sides of the screen as if they were arranged in a circle? I could then move from the left screen to the right screen, by simply moving the cursor to the left. I assume that the multimeter should read 2A, why is it only 0.358A? If this is how it is supposed to be, why? If I add a load, how do I measure that this load is being drawn, does the multimeter need to be in series? Project Euler Question 14 (Collatz Problem) If rest mass does not change with $v$ then why is infinite energy required to accelerate an object to the speed of light? I know that as the velocity increases, the mass of the object also increases so it becomes tougher and tougher to move the object which ultimately leads to a requirement of infinite energy to accelerate an object to the speed of light. But I have a doubt.  As far as I know only the observable mass (Relativistic mass) increases but not the Proper Mass or Intrinsic Mass, right? The actual mass of the object will remain the same. So if the actual mass ($m_0)$ remains the same and only the observable mass increases, why is more and more energy required? I know that even if the object exceeds the speed of light, we will not be able to say that it is moving faster than the speed of light but is it possible to make it move faster than light?  If rest mass does not change with $v$ then why is infinite energy required to accelerate an object to the speed of light?  I quote Igor Ivanov (a stackexchange user from this question ) to give an insight into my question.     The mass (the true mass which physicists actually deal with when they calculate something concerning relativistic particles) does not change with velocity. The mass (the true mass!) is an intrinsic property of a body, and it does not depends on the observer's frame of reference. I strongly suggest to  popular article by Lev Okun, where he calls the concept of relativistic mass a "pedagogical virus".   EDIT  After reading the answers I have a doubt.  SO can I say that only the overall energy of the system increases while the mass remains constant? But then if mass remains constant, then why is more and more energy gradually required? I mean there should be a reason for that requirement of infinite energy. "error: XDG_RUNTIME_DIR not set in the environment." when attempting to run nautilus as root I am attempting to run nautilus as root but when I run "sudo nautilus" from the terminal, I get the following error:     error: XDG_RUNTIME_DIR not set in the environment.      (nautilus:9341): Gtk-WARNING **: cannot open display:   The issue does not occur when I attempt to run nautilus as non-root. I am using ubuntu 14.04. Does anyone know how I can fix this?