Can I mix dual-rank and single-rank ram for my Dell XPS 15 9750 laptop
Can we mix dual-rank and single-rank DDR4 RAMs
An English book tells me that the following sentence is correct:     This publication is made from paper from sustainable forests.   Shouldn't it be of paper instead? Negative energy levels in the diagram for a hydrogen atom The higher the number of the shell (n), the higher is the energy level of the electron. However, why was it necessary to have negative values. So for example, when $n=1$, the energy could be $5 eV$ and for $n=2$, $6 eV$... having positive values could also have supported the idea that as $n$ increases, energy of electron increases. What is the point of having negative numbers, does it somehow aid calculations? How to count number of words from String using shell Android - Call log/ history : Retrieve a dialed number when there was no network coverage I dialed a number when I had no network support but it does not appear in the call history of my android phone.  Is there any way to get it ? (system logs or whatever)  THanks a lot in advance, Jack If my Schengen visa starts on the day of arrival which is one day ahead of departure, would they let me get into the plane? I have a question, I applied for the Schengen visa through Germany, on the form they ask me when I'd arriving (to Germany) and when I'd returning. they take this exact date as the visa period.  I wondering if they would let me get into the plane, even though my flight it a day before the arrival.  Let get the real deal; let say this:  My visa is valid from 02/12/2014 to 02/02/2015. But, my flight is scheduled to be departing on 01/12/2014, but entering Germany 02/12/2014. the flight duration is almost 9hours and there is 7hours difference between Germany and the departing flight country. Splitting words into specific fragments Why $(a+d)(b+c)$ equals $-16$? If $a,b,c$ and $d$ satisfy the equations:$$a+7b+3c+5d=0$$$$8a+4b+6c+2d=-16$$$$2a+6b+4c+8d=16$$$$5a+3b+7c+d=-16$$ then $(a+d)(b+c)$ equals $-16$.   I can't understand why $(a+d)(b+c)$ equals $-16$? Let $f:\Bbb{R}\to\Bbb{R}$ be a function given by  $$f(x)=\begin{cases} \exp\left(\frac{1}{x^2-1}\right) &amp; \text{if }\vert x\vert\lt 1\\  0 &amp; \text{if }\vert x\vert\geqslant 1  \end{cases}$$  I would like to prove that $f\in C^\infty$, that is, $f\in C^k$ for all $k\in \mathbb{N}$. I think that it can be done by induction on $k$. If $\vert x\vert\gt1$, the problem is trivial. On other points, the base case is the simplest and the only that I'm be able to do. Can someone help me?  Thanks. Isn't the const modifier here unnecessary? I read this book in Middle School and I can't for the life of me remember the title, but I can remember what it was about for the most part:  Takes place in the future, the government imposes laws that outlaw people from being different in appearance and skill level. For example, if you are fast or strong or tall, they will put weights on you to weigh you down so that you'll be more slower/shorter and more like the average. Another example, if you are pretty the government issues you "ugly glasses" etc.  Basically, it's all about making sure everyone is equal and punishing the extraordinary.  One of the main characters (a man) decides to literally loose himself of his shackles and weights, breaking them to display his power (if I'm remembering correctly).   Any ideas folks? Narrow-phase collision detection algorithms How to disable Spotify indicator in the top panel? The Spotify indicator icon clashes with the native Unity theme, and is redundant, since it is already listed in the Sound indicator menu. Is there a way to remove or disable the Spotify indicator? Or at least to change the icon (couldn't grep it on my filesystem). I am using the Spotify "preview" with 12.04. Thanks! I have one bash source run.sh as follows,  #!/bin/bash if [ $# -ne 1 ]; then     exit fi ...   when I execute it in two ways, there are different behaviors. The first way is,  source run.sh   It will close the terminal after execution. The second way is,  ./run.sh   this will simply finish running the script, and stay on the terminal. I am asking if there is a command for exiting a bash scripts for both source run.sh and ./run.sh execution. I have tried return too, which does not work well under ./run.sh execution.  More generally, I am interested in why this is happening, and what's difference between using "source" and "." for script execution? Prove $[\sin x]' = \cos x$ without using $\lim\limits_{x\to 0}\frac{\sin x}{x} = 1$ I came across this question:   From the comments, Joren said:     L'Hopital Rule is easiest: $\displaystyle\lim_{x\to 0}\sin x = 0$ and $\displaystyle\lim_{x\to 0} = 0$, so $\displaystyle\lim_{x\to 0}\frac{\sin x}{x} = \lim_{x\to 0}\frac{\cos x}{1} = 1$.   Which Ilya readly answered:     I'm extremely curious how will you prove then that $[\sin x]' = \cos x$   My question:  is there a way of proving that $[\sin x]' = \cos x$ without using the limit $\displaystyle\lim_{x\to 0}\frac{\sin x}{x} = 1$. Also, without using anything else $E$ such that, the proof of $E$ uses the limit or $[\sin x]' = \cos x$.    All I want is to be able to use L'Hopital in $\displaystyle\lim_{x\to 0}\frac{\sin x}{x}$. And for this, $[\sin x]'$ has to be evaluated first.    Alright... the definition that some requested.   Def of sine and cosine: Have a unit circumference in the center of cartesian coordinates. Take a dot that belongs to the circumference. Your dot is $(x, y)$. It relates to the angle this way: $(\cos\theta, \sin\theta)$, such that if $\theta = 0$ then your dot is $(1, 0)$.  Basically, its a geometrical one. Feel free to use trigonometric identities as you want. They are all provable from geometry. I would like to install Office 2015/365 on Ubuntu 15.04. I tried to install Office using Wine, but that did not work. Please note that I do not want virtualisation unless it has a -like behaviour, where application windows are treated like regular Ubuntu application windows by the system. How can I see flags I cast from all sites? How many solutions has the equation $\sin x= \frac{x}{100}$ ? How many solutions has the equation $\sin x= \frac{x}{100}$ ?   Usually when I was asked to solve this type of problem, I would solve it graphically but this one seems to be trickier. It doesn't seem wise to put $f(x)=\sin x$ and $g(x)=\frac{x}{100}$ in the same graph and then counting all the intersection points.  What would be some algebraic methods to solve this? Why is it called an “Indian file”? Proving the so-called "Well Ordering Principle" Is there anything wrong with the following proof?  Theorem. Every non-empty subset $B \subset\mathbb{N}$ has a least member.  Proof. Assume not. Then, of necessity, we'd have to have $B=\varnothing$, for if $B$ contained even one $b\in\mathbb{N}$, then that $b$ would satisfy $b=min(B). $ Contradiction, end proof.  I get the sense there is something wrong here, but I can't seem to define exactly what. Also, is there a context where one can simply take this principle as an axiom, and not have to prove it? After all, it is extremely intuitive. Thanks. Intuition for multiple temporal dimensions It’s easy, relatively speaking, to develop an intuition for higher spatial dimensions, usually by induction on familiar lower-dimensional spaces. But I’m having difficulty envisioning a universe with multiple dimensions of time. Even if such a thing may not be real or possible, it seems like a good intellectual exercise. Can anyone offer an illustrative example?