Cannot connect Ubuntu 18.04 to Wifi
Installing Wi-Fi driver for Realtek Semiconductor RTL8723DE Device [10ec:d723]
Expansion of $(1+\sqrt{2})^n$ I was asked to show that $\forall n\in \mathbb N$ there exist a $p\in \mathbb N^\ast$ such that $$(1+\sqrt{2})^n = \sqrt{p} + \sqrt{p-1}$$   I used induction but it wasn't fruitful, so I tried to use the binomial expansion of $(1+\sqrt{2})^n$ but it seems I lack some insight to go further.   Any hint is welcomed. How can I pad an integer with zeros on the left? After the recent "Look and Feel" Apple vs Samsung lawsuits, I've been wondering to what extent this might affect websites/webapps that offer functionality similar to other existing sites.  So what exactly would one have to be wary of to make sure they don't step on the toes of a big corporation?  I could see carbon copying a companies website/app (especially if it's a very distinctive product) being a bad practice that could get you some backlash, especially blatantly ripping off iconic terminology, but how similar is too similar?  Does the ten-foot rule apply to the web?     “If a reasonable person could not, at ten feet, tell the difference between two competitive products, then there was cause to believe an infringement was occurring.”   Or is there a separate legal precedent associated with the web?  And then where does feel, which is essentially the common term for UX, come in.  Can you patent the way a website "feels", as in the flow, organization and functionality associated.  I understand that you can't patent basic elements like radio buttons, but what about the layout and look of a large number of those elements used in combination to complete a certain action/s?    I know that is still a bit of a Sword of Damocles for online retailers.  Where is the line drawn for website/webapp copyright infringement?  Or is there even a line drawn yet? Does the pilot of a rocket ship experience an asymptotic approach to the speed of light? Can I smoothly upgrade from one LTS to next LTS release? My problem is that I have only one reference. So I would like the head of this part to appear "Reference" instead of commonly "References". More generally, could we change the title "References" to an arbitrary name?  Thank you very much for your help! How to make a cross-module variable? “May I know your good name?” "May I know your good name” is a typically Indian way of honouring another person by asking their name using an adjective like sweet, good, beautiful, et cetera. Of course there won’t ever be any bad or sour name (unless we feel it such) when asking.   If this manner of asking someone’s name is incorrect or inappropriate, then how could I make it sound more polite and amicable without negotiating the basic principles of English? Connect MacBook Pro to two external monitors Is there a way to connect my MacBook Pro to two external monitors (either VGA or HDMI; no Thunderbolt) in such a way that the Mac screen serves as a third monitor?  What hardware do I need? Why is "No new release found" when upgrading from a LTS to the next? A Google search spewed forth millions of hits on how to find tables without clustered indexed, the PK normally being the clustered index of a table. However, a table could easily have a natural key as a clustered index, and a non-clustered surrogate index, like an identity column.  How do I find all tables in a DB without a primary key defined? I have 245 tables in this DB: manual inspection is grossly inefficient. Chrome always quit when I click on the X button on a tab, without asking me anything!  Even when I close Chrome he do not alert me if I am willing to relay close it?   Many times it happened that accidentally I clicked on X button. Schengen Visa Application: what are some helpful tips for preparing? Registered Apple Developer Agreement when under 18 Manipulating the axis on a ListLinePlot cd into all directories, execute command on files in that directory, and return to previous current directory I'm attempting to write a script that will be run in a given directory with many single level sub directories. The script will cd into each of the sub directories, execute a command on the files in the directory, and cd out to continue onto the next directory. What is the best way to do this? Say there are $m+n$ elements split into two groups ($m$ and $n$). The variance of the first group is $\sigma_m^2$ and the variance of the second group is $\sigma^2_n$. The elements themselves are assumed to be unknown but I know the means $\mu_m$ and $\mu_n$.  Is there a way to calculate the combined variance $\sigma^2_{(m+n)}$?   The variance doesn't have to be unbiased so denominator is $(m+n)$ and not $(m+n-1)$. What happens when a familiar from the Find Familiar spell "dies"? Keeping an updated balance (Accounting) I have been struggling trying to find a way to properly and reliably maintain a balance for accounts in an order/payment system.  Currently, the process consists of three tables. Below example is very simplified but gets the point across.  Table one contains the account ID, name, total paid, total orders, balance etc.  Table two contains payments, date, the account ID (FK) and amount.  Table three contains orders, date, the account ID (FK) and amount.  Calculating the balance is of course as easy as  SELECT SUM(payments.AMOUNT) FROM payments WHERE ID = [account] SELECT SUM(orders.AMOUNT) FROM orders WHERE ID = [account]   Followed by some simple addition/subtraction math:  UPDATE accounts SET BALANCE = [balance] WHERE ID = [account]   All good - the problem is - how do I maintain this over let's assume years of activity and many, many transactions?  Currently the accounts table is updated every single time a transaction is made, meaning the above three statements run every time. There is of course an index on the ID column in all three tables, and everything is fast and neat for now, but I work with less than 100,000 transactions, meaning everything fits into the RAM and basically all I throw at the database gets executed immediately. Over time this will change, of course - so how do I handle this?  Is it better to mark the accounts as "dirty" and process balancing in a batch job later, or can I keep updating the balance real-time even when I reach the point where the orders and payments tables will not fit into the RAM?  Do I need to segment the orders and payments and "lock" everything before a given time, such as before last calculation? (I would rather not). I ask because then I could do a SUM WHERE DATE > [last lock timestamp] and update with UPDATE BALANCE = [balance] + [value for last lock] and prevent the problem from outgrowing resources.  I don't need a running balance for each transaction. That's all I can find results for when I try to research this problem. I just care about the total amount paid, the total amount ordered and the balance of accounts.  Why don't I calculate on the fly when I need the balance, you ask? Because one must be able to query the system and ask "Which of my (let's say) 50.000 accounts have a balance below 0?" - something we cannot do easily if we do not store the balance with every account. What is a good word to describe 'exceptional positive' research work?