How to reset multiple select boxes in a form with jquery?
Reset select value to default
Script to change current directory (cd, pwd) I want to run a script to simply change the current working directory:  #!/bin/bash cd web/www/project   But, after I run it, the current pwd remains unchanged! How can I do that? How can I use ranges in a switch case statement using JavaScript? access parent object in javascript I run a guest ubuntu 12.04 on a host ubuntu 12.04, with VirtualBox, and the guest is much, much slower than the host (ALT+TAB takes 4-5 secs). I had a look around and I found contradicting opinions on VirtualBox versus VMware (free); so I thought to keep the former.   Both systems are updated, I installed the additions on the guest and I evenly split memory and video memory (64MB) between guest and host. I am running a Toshiba m200 laptop with 4GB ram and shared video memory. The host bios does not include a configuration option for machine virtualization. I have 2 cpus and I can't give them both to the virtual machine.  Is there anything I overlooked that could solve my problem?  Feel free to ask for more info, and thank you for any help.  EDIT Idling with the system monitor open the (single) guest cpu never gets below 55% and could rise to 80 - 90% just by moving the mouse around. Opening Firefox will cause the system monitor to show cpu usage 100% in the guest, while the host shows that both cpus are evenly working around 60%.  My cpu is Intel® Core™2 Duo CPU T5450 @ 1.66GHz × 2.  If this is not a configuration problem, does it mean my machine is too weak for virtualization? $$ x^2+2(1+a)x+(3a^2+4ab+4b^2+2)=0$$  I tried to make an inequality using the discriminant and I simplified it to get $$a^2+2ab+b^2+\frac{1}{2}≤0$$  But I don't know how to solve this. Why is $1$ not considered a prime number?  Or, why is the definition of prime numbers given for integers greater than $1$? Simple way to monitor a multiple URLDownloadSubmit calls? How can I scale all images in a folder to the same width? I want to scale all images in a given folder to the same width (but different appropriately scaled heights). How can I do this using  a GUI-based or command-line tool?  For bonus points, is it possible to restrict which images are scaled based on their initial width (that is, only scale images that have a width > x and/or a width &lt; y)? In the previous version the logout button is under your username, which it can be found by clicking the down arrow. However, in the new version, after a couple minutes of searching, it is under the "site-switcher" button:        This is really illogical since the logout button is usually under your username, including Google and Yahoo! services.  I suggest bringing back the  which will definitely benefit new users and even old users. Submitting a URL to Google using PHP/cUrl Is there a difference between SWAP and Cache memory? I installed the indicator-multiload 0.2-0ubuntu1 from the software center. (It's very similar to the gnome panel indicator showing memory and CPU graphs)  When I click on the Unity panel which shows the little memory graph, it says ;  Mem :1.451 GB   Cache: 2.581.  This is also represented in the color graph.  However, when I load the System Monitor, SWAP is at a flat 0.  Is this normal, or could there be a bug in either the System Monitor or Panel Indicator? Why does an argument similiar to 0.999...=1 show 999...=-1? I accept that two numbers can have the same supremum depending on how you generate a decimal representation. So $2.4999\ldots = 2.5$ etc. Can anyone point me to resources that would explain what the below argument that shows $999\ldots = -1$ is about? Here is the most usual proof I see that $0.999\ldots = 1$:  $x=0.999\ldots$ $10x=9.999\ldots$ $10x - x = 9$ $x=1$  Using this same argument template I can show $999\ldots=-1$:  $x= \ldots9999.0 $ $0.1x= \ldots9999.9$ $0.1x - x = 0.9$ $x=-1$  What might this mean? Edit from one of the comments: $$\sum_{k=0}^{\infty}{9 \cdot 10^k}=-1$$ MT7610U - Unable to install wifi driver How to make two people play at the same time? My brother owns Skyrim on steam. We use Steam Family Share, but we were wondering how both of us could play it at the same time? How do I install Ubuntu 16.04 from an SD card? Could someone explain how to install Ubuntu from an SD card? I don't have any CDs or USB sticks around. My current operating system is Windows 10 64 bit. I want to use a Java file SaveProp which is written in a package user. The class file has been placed in WEBINF/classes. Below are the two lines which cause the issue.  jsp:useBean id="user" class="user.SaveProp" scope="session"  jsp:setProperty name="user" property="*"   It throws:  The value for the useBean class attribute user.SaveProp is invalid   I'm using Tomcat 6.0. How many syllables are in the word 'hour'? Does the word 'hour' have 1 or 2 syllables? I resized the root partition with GParted, from 20 GB to 40 GB, but the filesystem still reports a size of 20 GB.  How can I use all 40 GB?    Update  The resized partition was an LVM Physical Volume (/dev/sda2), and the boot partition is ext4 (/dev/sda1). Pure significance of line integrals of vector fields I can understand how the line integral of a scalar function has pure-mathematical significance, representing an area beneath a curve. But is there a pure significance to the line integral of a vector field? The only understanding I have of this is the physical example of work done on a moving particle. Thanks for any insight. Let $(A,+,\cdot)$ be a unity ring with the property that if $x \in A$ and $x^2=0$ then $x=0$. Consider the set $M=\{a\in A | a^3=a\}$. Prove that:      a) $2a\in Z(A)$, $\forall a\in M$, where $Z(A)$ denotes the centre of the ring $A$;   b) $ab=ba$, $\forall a,b\in M$.   My attempts revolved around the fact that an idempotent element in a reduced ring is central. So, since for $a\in M$ we have that $(a^2)^2=a^2$, it follows that $a^2\in Z(A)$, $\forall a\in M$. The next thing I wanted to use in order to solve a) was that $Z(A)$ is a subring of $A$, so if I had proved that $(a+1)^2 \in Z(A)$, $\forall a\in M$, then we would have reached the desired conclusion. However, I couldn't prove this and I honestly doubt that it is true. Another idea that I had was to prove that $M$ is a subring of $A$. Of course, this didn't work out because I cannot even prove that $M$ is closed under addition. Again, I don't know if this is true and it most likely isn't. As for b), I think that a) should be of use, but I don't know how. It is a well-known problem that a ring with $x^3=x$ for any $x$ in that ring is commutative, but since $(M,+,\cdot)$ is almost definitely not a ring, this doesn't help. EDIT: Is there any chance that this question is simply wrong? I tended to believe this before asking it here too, but since nobody has made any progress on it until now I am even more inclined to think so.