i tried a lot of solutions but none seems work. For example this  two links:   The second link  suggest this solution: sudo add-apt-repository ppa:thopiekar/mt7601 The answer is:     Source code: (c) Copyright 2002-2013, MediaTek Inc. (released under GPLv2) GitHub: https://github.com/porjo/mt7601 Patches: @poma at linux-wireless mailing list  More info: https://launchpad.net/~thopiekar/+archive/ubuntu/mt7601 Press [ENTER] to continue or Ctrl-c to cancel adding it.  Ignorato:1 http://ppa.launchpad.net/thopiekar/mt7601/ubuntu focal InRelease Trovato:2 http://archive.ubuntu.com/ubuntu focal InRelease                      Errore:3 http://ppa.launchpad.net/thopiekar/mt7601/ubuntu focal Release           404  Not Found [IP: 91.189.95.83 80] Trovato:4 http://archive.canonical.com/ubuntu focal InRelease                   Lettura elenco dei pacchetti... Fatto E: Il repository &quot;http://ppa.launchpad.net/thopiekar/mt7601/ubuntu focal Release&quot; non ha un file Release. N: L'aggiornamento da tale repository non può essere eseguito in modo sicuro ed è quindi disabilitato come impostazione predefinita. N: Consultare la pagina man apt-secure(8) per la creazione di un repository e la configurazione utente.  At the end is written that the repository is note sicure and i have to go to the page &quot;man apt-get secure&quot; to make a repository and the id configuration Can someone help me? Thanks
When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?
How Do I Allow A Standard User to Install Programs? What are the prerequisites to encounter the legendaries in ORAS? There are a lot of legendaries available in ORAS, however a lot of them will only show up/be available if certain prerequisites are met.  I know Groudon/Kyogre are available through the Story, and      Rayquaza &amp; Deoxys   through the postgame Delta episode, but what about the other available legendaries? What do I need to do to catch them? I don't know how many of you have experienced the  principle when posting questions on SO, but I know I have on a few occasions. And then I just discard my question. So here's the question:  Should we go ahead and post the question?  Of course if it's something stupid like forgetting a semicolon, etc., I would say no... but there are several occasions, like if a data structure doesn't make sense, that at least someone would eventually benefit from the question/answers.  And if you should ask the question, how would you recommend choosing an answer for it? I am getting a NoClassDefFoundError when I run my Java application.  What is typically the cause of this? What is a Pythonic way to pad a numeric string with zeroes to the left, i.e. so the numeric string has a specific length? How to leave body of question empty? What should I look for when shopping for my first DSLR? I am thinking of buying a digital SLR camera. What things should I be looking for? If $\mathbf A$ and $\mathbf B$ are Hermitian, when does $\det(\mathbf A-\lambda\mathbf B)=0$ have only real roots? Let $\mathbf A, \mathbf B$ be Hermitian matrices of the same size. What is the characterization of $\mathbf A, \mathbf B$ such that $p(\lambda)=\det(\mathbf A-\lambda\mathbf B)=0$ has only real roots?   If $\mathbf B$ is positive definite (I corrected this), it is easy to see $p(\lambda)$ has only real roots. Can a function be made to accept a variable amount of inputs? Install App Image such as beaker browser and pin it to dock (favorites) in Ubuntu 20.04? Get PHP to stop replacing '.' characters in $_GET or $_POST arrays? If I pass PHP variables with . in their names via $_GET PHP auto-replaces them with _ characters. For example:  &lt;?php echo "url is ".$_SERVER['REQUEST_URI']."&lt;p&gt;"; echo "x.y is ".$_GET['x.y'].".&lt;p&gt;"; echo "x_y is ".$_GET['x_y'].".&lt;p&gt;";   ... outputs the following:  url is /SpShipTool/php/testGetUrl.php?x.y=a.b x.y is . x_y is a.b.   ... my question is this: is there any way I can get this to stop? Cannot for the life of me figure out what I've done to deserve this  PHP version I'm running with is 5.2.4-2ubuntu5.3. I've been told that I should use simple past in reported speech when the direct speech is in simple present such as I **am** the best   ~>   He said he **was** the best  but what happens for imperative mood direct speech     "Mom said dont trust strangers"   Or     "Mom said didn't trust strangers"   I think I should maintain the first form. But I'm not sure. And I'm not even sure this relates to the sentence mood. I need the best choice and a further explaination for this :) Probability of the union of $3$ events? I need some clarification for why the probability of the union of three events is equal to the right side in the following:  $$P(E\cup F\cup G)=P(E)+P(F)+P(G)-P(E\cap F)-P(E\cap G)-P(F\cap G)+P(E\cap F\cap G)$$  What I don't understand is, why is the last term(intersection of all) added back just once, when it was subtracted three times as it appears from a Venn Diagram?  Here on page 3, this is explained but not in enough details that I can understand it: Which method performs better: .Any() vs .Count() > 0? in the System.Linq namespace, we can now extend our  to have the  and  extension methods.  I was told recently that if i want to check that a collection contains 1 or more items inside it, I should use the .Any() extension method instead of the .Count() &gt; 0 extension method because the .Count() extension method has to iterate through all the items.  Secondly, some collections have a property (not an extension method) that is Count or Length. Would it be better to use those, instead of .Any() or .Count() ?  yea / nae ? Various \textcolor within lstlisting? Benefits and Drawbacks of Swapping Associations of Positivity and Negativity of the Proton and Electron For historical reasons, I understand that a proton's charge was assigned the label of "positive", the electron's charge was assigned the label of negative, and, crucially, equations of current in E &amp; M are written with the notion that current is the flow of positive charge despite the rarity of actual flows of protons in real systems (which I understand are mostly biological systems).   If the possibility existed to instantaneously and at no cost, retcon these associations such that protons have a negative charge, electrons have a positive charge, and current remains the flow of positive charge, would there be any beneficial or detrimental outcomes?  For instance, would there be:   new interpretations of physical laws that would provide different or better insights into any relevant subfield of Physics significant simplifications to notation in any field of Physics or Engineering significant increases in understanding in the fields of electricity, electronics, electrical engineering, radiation/radiative transport, etc. a noticeably easier learning curve for any subfield of physics dealing with the concept of charge   Additionally, is there a permutation of positive charge, negative charge, and flow of current definition that would improve upon the one I suggested? How do I change the shortcut-key of show the unity dash? I don't want to use the Super for that, I want to use Alt+Space instead. Prove $[A,B^n] = nB^{n-1}[A,B]$ I am trying to show that $[A,B^n] = nB^{n-1}[A,B]$ where A and B are two Hermitian operators that commute with their commutator. However, I am running into a little problem and would like a hint of how to proceed.  If A and B commute then $[A,B] = ABA^{-1}B^{-1} = e$ where e is the identity element of the group.  $$\therefore AB=BA$$  $$n=1; [A,B^1] = (1)B^0[A,B] = e$$ This statement is certainly true. however moving on to $n = 2$ I find...  $$[A,B^2] = AB^2A^{-1}B^{-2} = ABBA^{-1}B^{-1}B^{-1} = BBAA^{-1}B^{-1}B^{-1}$$  Where in the last step I have used the fact that A and B commute to rearange the terms. However, it is plain to see that this last term simply reduces to the identity as well and for the n = 2 case we have:  $$[A,B^2] = e \ne 2B[A,B] = 2Be = 2B$$  Clearly I have assumed something I shouldn't have. The fact that there is a multiplicative factor of n implies I should be adding things, but I thought if I kept it as general as possible, the answer should just fall out naturally. I don't want an answer please, only guidance. CSS two divs next to each other What are these fuse-looking cartridge case components on small, battery operated RF tranceivers? I have recently opened up 3 dead, battery-operated RF transceivers lying around, both wearable and key-chains. I've noticed that all three had components that looked like fuses (cartridge case), soldered down, that are quite large compared to the size of the circuit. See the pictures below. I'm not posting full circuit pictures because I don't know if I should, I can update if they are necessary.  Device 1:    Device 2:    Device 3:    I can't see why such a device will require a fuse, and I couldn't find any other common components manufactured in cartridge cases, maybe I'm not using the correct name. I don't see them on any applications notes or reference designs for the ICs used either.  I've tried to figure out how they are connected to the circuit, I don't have schematics and PCBs are more than 2 layers so they may not be complete, but see the schematics I've figured below.  Device 1:    Device 2:    Device 3:    Also, when I do a continuity test between the terminals of the components with a multimeter, resistance starts in ~50 Ohms range and goes down to short as I keep the probes on its terminals so my best guess is something for ESD protection, maybe Varistors or Thermistors?   Does anyone know what these components are and why they are there?