My headphone jack and my speakers are not working at all. They just randomly stopped when my macbook air was closed. Is there any system preferences that i need to change?
Periodically, my MacBook Pro 17" stops recognizing my headphones. No amount of unplugging and replugging seems to help. The sound settings never show headphones as an output device. How can I fix this? The only thing I can find elsewhere on the Internet are people saying, "Reboot!" This works, but is impractical and annoying.
If $\lambda$ is an eigenvalue of $A^2$, then either $\sqrt{\lambda}$ or $-\sqrt{\lambda}$ is an eigenvalue of $A$ $A$ is an $n\times n$ matrix of complex numbers. Prove that if $\lambda$ is an eigenvalue of $A^2,$ then $\sqrt{\lambda}$ or $-\sqrt{\lambda}$ is an eigenvalue of $A.$    If $\lambda$ is an eigenvalue of $A^2,$ we have $\lambda\alpha=A^2\alpha$ for some $\alpha.$ Then how can we find a $\beta$ s.t. $\sqrt{\lambda}\beta=A\beta?$ Were I rich, I would live on Long Island.   If I were rich, I would live on Long Island.   Is the first sentence still used, or is used in particular contexts (in example, to give emphasis to the sentence)? I will soon be attending a Ph.D program in mathematics. I do not know how common this practice is, but the department has a requirement that graduate students must learn a foreign language and be able to read and write mathematics in that language. The three choices are French, German, or Russian. I personally have no preference on which to learn, but I was wondering if there were other reasons that would make one language more advantageous over the others in terms of a general mathematical career. Thanks in advance in any response. Remove default ID attribute from HTML helpers in ASP.NET MVC Prove existence of a real root. Problem: If   $$C_0+\frac{C_1}{2}+\cdots + \frac{C_{n-1}}{n}+\frac{C_n}{n+1} =0,$$  where $C_0,...,C_n$ are real constants, prove that the equation  $$C_0+C_1x+\cdots +C_{n-1}x^{n-1}+C_nx^n=0$$  has at least one real root between $0$ and $1$.  Source: W. Rudin, Principles of Mathematical Analysis, Chapter 5, exercise 4. How can I identify what application is using a given file? I'm trying to delete some folder but this error is preventing from doing it:     Cannot delete [FileName]: It is being used by another person or program.      Close any programs that might be using the file and try again.   How can I identify what application is using the file?   I want to end the application using a Task Manager, but I didn't know what application is using it.  The folder is not shared and my user account is an administrator. Can I safely charge my laptop with a non-standard, third-party charger? I have a Toshiba Satellite laptop. My charger has stopped working.  I have access to a Lenovo charger. Can I use this charger on my laptop? My PC (Lenovo Ideapad z580) is overheating while running Ubuntu GNOME 16.04 LTS.  $ uname -a Linux Mahadev 4.4.0-72-generic #93-Ubuntu SMP Fri Mar 31 14:07:41 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux  $ lspci -nnk|grep -A2 VGA 00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)   Subsystem: Lenovo 3rd Gen Core processor Graphics Controller [17aa:3977]   Kernel driver in use: i915   $ sensors acpitz-virtual-0 Adapter: Virtual device temp1:        +52.0°C  (crit = +104.0°C)  coretemp-isa-0000 Adapter: ISA adapter Physical id 0:  +54.0°C  (high = +72.0°C, crit = +90.0°C) Core 0:         +54.0°C  (high = +72.0°C, crit = +90.0°C) Core 1:         +54.0°C  (high = +72.0°C, crit = +90.0°C)  update vivek@Mahadev:~$ stress -t 300 -c $(getconf _NPROCESSORS_ONLN) &amp;&amp;  sensors stress: info: [4408] dispatching hogs: 4 cpu, 0 io, 0 vm, 0 hdd stress: info: [4408] successful run completed in 300s acpitz-virtual-0 Adapter: Virtual device temp1:        +73.0°C  (crit = +104.0°C)  coretemp-isa-0000 Adapter: ISA adapter Physical id 0:  +72.0°C  (high = +72.0°C, crit = +90.0°C) Core 0:         +69.0°C  (high = +72.0°C, crit = +90.0°C) Core 1:         +72.0°C  (high = +72.0°C, crit = +90.0°C)  update     vivek@Mahadev:~$ sudo lshw -C cpu     [sudo] password for vivek:    *-cpu                             description: CPU         product: Intel(R) Core(TM) i3-3110M CPU @ 2.40GHz         vendor: Intel Corp.        physical id: 0        bus info: cpu@0        version: Intel(R) Core(TM) i3-3110M CPU @ 2.40GHz        serial: To Be Filled By O.E.M.        slot: CPU Socket - U3E1        size: 1302MHz        capacity: 2400MHz        width: 64 bits        clock: 100MHz        capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr  pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx  fxsr sse sse2 ss ht tm pbe syscall nx rdtscp constant_tsc arch_perfmon  pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni    pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid    sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer xsave avx f16c lahf_lm    epb tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt     dtherm arat pln pts cpufreq           configuration: cores=2 enabledcores=2 threads=4  Update This time I edited the sensors , htop command result in image. It's getting overheated, my laptop is getting hang cause of overheating, please watch and reply. Thanks. Energy conservation and interference I have a problem with energy conservation in case of interfering waves.  Imagine two harmonic waves with amplitudes $A$. They both carry energy that is proportional to $A^2$, so the total energy is proportional to $2A^2$. When they interfere, the amplitude raises to $2A$, so energy is now proportional to $4A^2$ and bigger than before.  The equivalent question is what happens to the energy with the superposition of two waves that interfere destructively.  Also, if someone could comment on the statement about this problem in my physics book (Bykow, Butikow, Kondratiew):      The sources of the waves work with increased power during the interference because they feel the wave from the other source. How to do a bias-variance analysis on a machine learning modelling process Limit of $s_n = \int\limits_0^1 \frac{nx^{n-1}}{1+x} dx$ as $n \to \infty$ Let $s_n$ be a sequence defined as given below for $n \geq 1$. Then find out $\lim\limits_{n \to \infty} s_n$.   \begin{align}   s_n = \int\limits_0^1 \frac{nx^{n-1}}{1+x} dx  \end{align}  I have written a solution of my own, but I would like to know it is completely correct, and also I would like if people post more alternative solutions. How to find all graph isomorphisms in FindGraphIsomorphism The forgetful functor $\mathsf{Groups} \to \mathsf{Sets}$ admits a left adjoint, namely, "forming the free group" functor.  I was wondering if this has a left adjoint.  This seems unlikely, but I don't have a proof.  Is there a functor $\mathsf{Sets} \to \mathsf{Groups}$ that admits a left adjoint at all? How to use variable inside parameter $_GET? example: ($_GET[$my_var]) In The Matrix Reloaded, the Architect reveals to Neo that Trinity is about to die. I can't help but wonder if Neo would still choose the left door if the Architect had withheld that information.  The Architect could have designed a better choice mechanism so as to trick Neo into making a choice in the machine's favor rather than a highly risky one.   Did I miss anything important in the movie? Is my ESTA valid for a second trip? I visited the USA in May this year, on an ESTA which I applied for in April. It was approved and I was allowed entry into the country.    I'm re-visiting again this November for two weeks. Am I able to use the same ESTA again or do I need to re-apply for a new one? I know it says it's valid for two years, but is that valid for every use within those two years, or I have to use it within two years, and once I have visited on that visa, it's invalid? Can I get an enters-the-battlefield effect out of a second legendary before I must sacrifice it? If I have a legendary creature out, and I make a copy of it (such as by enchanting it with  or making a ), do I get enters-the-battlefield effects from the creature before I have to sacrifice it to the legend rule? Why are the objects in my hair particle system not sitting on top of the ground? I made a hair particle system and set the Dupli Group to a group of 3 objects. Each of the 3 objects has:   it's origin set to be touching the XY plane (on layer 2) it's Scale applied to 1 and it's Rotation applied to 0     I am trying to get each of the objects to sit directly on top of the ground, but instead, they are centered in the plane, half above the plane and half below the plane:      What am I doing wrong? Here is . How can I edit this trigger to only fire once? The trigger creates a related record when a checkbox is updated. The problem is it is creating a new related record everytime the record is edited. I want to edit the trigger to only create the related record once. (When the criteria is first met). The code is below  Trigger copyEquipmentonsite on Unit_Placements_Sales__c(after insert, after update) {      List&lt;Services__c&gt; sub=new List&lt;Services__c&gt;();      for(Unit_Placements_Sales__c u : Trigger.new) {           if(u.Service_Month_is_Next_Month__c == TRUE) {                 Services__c s = new Services__c();                 s.Equipment_Onsite__c=u.ID;                 s.Equipment_Type__c=u.Equipment__c;                 s.Machine_Specific_Notes__c=u.Machine_Specific_Notes__c;                    s.Product__c=u.The_Product__c;                   s.Dell_Tag_Number__c=u.Dell_Tag_Number__c;                 s.Serial_Number__c=u.Serial_Number__c;                  s.XD_Number__c=u.XD_Number__c;                 sub.add(s);           }           if(sub.size()&gt;0)           insert sub;      } } I'm using Java, and need to generate a simple, standards-compliant RSS feed. How can I go about this?