I know this isn't a research level question, but a lot of you teach, and I'm not sure where else to turn.  I will just shoot straight: I am 30 years old. I have not done any type of true mathematics in over 10 years. In the preceding decade, I have forgotten everything I've ever known about mathematics.  Do any of you know of any sites that offer free lessons in algebra 1, geometry, etc?  Perhaps computer games that deal with high-school level math?  Again, I apologize for posting this here, but I'm anxious to restart my career as a student--something I can't do until I bring my math skills up to par.
I'm looking for mathematics books, courses + exercises for high school level. My daughter was high school certificated but she has stopped her studies for 5 years. She would like to be involved in new educational program but she needs to restore her mathematic capabilities.  Could you help me to identify which mathematics books can help her?  Thanks a lot for your reply,  FR.
When should you use struct and not class in C#? My conceptual model is that structs are used in times when the item is merely a collection of value types.  A way to logically hold them all together into a cohesive whole.  I came across these rules :   A struct should represent a single value. A struct should have a memory footprint less than 16 bytes. A struct should not be changed after creation.   Do these rules work? What does a struct mean semantically? List of functions not integrable in elementary terms When teaching integration to beginning calculus students I always tell them that some integrals are "impossible" (with a bit of expansion on what that actually means).  However I must admit that the examples I give mostly come from "folklore" or guesswork.  Can anyone point me to a list (not a complete list of course!) of fairly simple elementary functions whose antiderivatives are not elementary?  I'm thinking of things like $\exp(x^2)$ which is the standard example, $\sin(\exp(-x))$ perhaps, things like this, not hugely complicated formulae. "the police conspiracy" vs. "the police's conspiracy" Few font size-related layout issues I am using a default font size of 26px and stackoverflow's layout seems to not work well with such a large sizes.  The most important issue is that many inputs tend to overflow and partially get hidden below side text. This includes one with login, ‘Title’ and — the most important issue — the editor, which makes writing posts a little painful.  Another important one is that sometimes 'search' field doesn't fit in topbar and jumps lower, being partially hidden by logo. I met that issue on stackoverflow itself only while serverfault &amp; meta display fine (but that may be related to rep or sth).  There's one minor issue too — navbar is too narrow and ‘Ask Question’ jumps below — but this one looks quite nice (maybe it's even intended?).  Screenshot: (click to enlarge) How do I save a variable or function definition to a file? Question about Casella and Berger's proof of MLE invariance In Casella and Berger, p. 320, they have a proof of the invariance of the MLE. Let $g: \theta \mapsto \eta$ be a function. They define the induced likelihood as  $$ L^*(\eta \mid X) = \sup_{\{\theta: g(\theta) = \eta\}} L(\theta \mid X). $$  This ensures that $g$ is one-to-one with respect to the likelihood functions because if $g$ is not one-to-one, there may be multiple values of $\theta$ that map to a given $g(\theta) = \eta$.  Then they note  $$ \sup_{\eta} L^*(\eta \mid X) = \sup_{\eta} \sup_{\{\theta: g(\theta) = \eta\}} L(\theta \mid X) = \sup_{\theta} L(\theta \mid X). $$  The first equality just applies the definition of the MLE of $\eta$. However, the next inequality confuses me. They write,     The second inequality follows because the iterated maximization is equal to the unconditional maximization over $\theta$...   Can someone justify this claim or provide some intuition if the claim is supposed to obviously follow from definitions? How to add a program as a startup application from a terminal? I am using Ubuntu 12.04 and I know the GUI way to maintain the startup program list but now I want to find out the way to add/remove startup applications using a command line interface (CLI). Ejecting a USB 3.0 drive connected to USB 3.0 port reconnects immediately I made a plot but it's not at all what I want. There are two things I'm having trouble with: 1.) The bars should be at the bottom, but there's a space between them and the x-axis. 2.) E1/E4, E2/E5 and E3/E6 should have the same color.  Here's a picture of how it is and how I want it below:   And here's my code:  \documentclass{standalone} \usepackage{pgfplots,pgfplotstable} \begin{document} \begin{tikzpicture} \begin{axis}[ symbolic x coords={E1, E4 (dyn.), E2, E5 (dyn.), E3, E6 (dyn.)}, xtick=data, width=\linewidth, height=6cm ] \addplot[ybar,fill=blue, bar width = 1cm] coordinates {     (E1,   8)     (E2,  15)     (E3,   50)     (E4 (dyn.), 4)     (E5 (dyn.), 17)     (E6 (dyn.), 40)  }; \end{axis} \end{tikzpicture} \end{document}   I hope you can help me. Thanks. PATH variable resets with reboot Do circular wheels maximize mechanical efficiency? I recently wondered whether there is a simple proof that circular wheels maximise mechanical efficiency. By this I mean:     Show that for a wheel with a given width and cross-sectional area, the   circular wheel reaches the bottom of an incline faster than a wheel   with any other shape.   This sounds like a rather elementary problem in classical mechanics but I haven't found a proof of this fact in any of the classical mechanics texts that I have read.   Note 1: I assume that the distribution of mass is uniform across the wheel so comparable wheels will have equal mass.   Note 2: Dry friction is assumed to be present. Converse to Chinese Remainder Theorem So as seen on this question , we know that if $(n,m) \neq 1$, then $\mathbb{Z} /mn \mathbb{Z} \ncong \mathbb{Z}/n\mathbb{Z} \times \mathbb{Z}/m\mathbb{Z}$, because the right hand side does not have an element of order $nm$.  But take a more general setting. Let $R$ be a commutative ring, and let $A,B$ be ideals in $R$. $A$ and $B$ are said to be comaximal if $A+B=R$. If $A, B$ are comaximal, then we have: $R/AB \cong R/A \times R/B$. In this setup, is the converse true?      If we have $A, B$ ideals in $R$ such that $R/AB \cong R/A \times R/B$, do we always have that $A$ and $B$ are comaximal? Debian based system, only one gui program, nothing else I would like to make a debian system where you can only open one GUI program at boot, no other graphical interface, no minimize, or any X apart from that program, is there a way to do it on debian if possible, or any other custom distro? I just want to boot open the program and allow the user to only see and use that program. Confirm and agree to negative questions Can I connect to SQL Server using Windows Authentication from Java EE webapp? I am currently investigating how to make a connection to a SQL Server database from my Java EE web application using Windows Authentication instead of SQL Server authentication. I am running this app off of Tomcat 6.0, and am utilizing the Microsoft JDBC driver. My connection properties file looks as follows:  dbDriver              = com.microsoft.sqlserver.jdbc.SQLServerDriver dbUser                = user dbPass                = password dbServer              = localhost:1433;databaseName=testDb dbUrl                 = jdbc:sqlserver://localhost:1433   I have zero problems with connecting to a SQL Server database in this fashion when using SQL Server authentication.  Is there any way I can retrieve the credentials of the user's Windows Authentication and use that authentication for SQL Server?  UPDATE: I know in ASP.net there is a way to set up Windows Authentication for access to the webapp, which is exactly what I am looking for, except I want to pass that token off to SQL Server for access to the database. How to work with Dried Mushrooms? I was recently given a bag of dried mushrooms and am unsure how to work with them.  What's the best way to use them? Javascript Closures and 'this' I have a problem with an object I have created that looks something like this:  var myObject = {      AddChildRowEvents: function(row, p2) {         if(document.attachEvent) {             row.attachEvent('onclick', function(){this.DoSomething();});         } else {             row.addEventListener('click', function(){this.DoSomething();}, false);         }     },      DoSomething: function() {         this.SomethingElse(); //&lt;-- Error here, object 'this' does not support this method.     } }   The problem is that when I am inside the 'DoSomething' function, 'this' does not refer to 'myObject' what am I doing wrong? How to play blu ray .mkv files on ubuntu 20.04 LTS? How to play blu ray .mkv files on Linux? e.g:1080p.BluRay.DD5.1.x264-NTb.mkv I am trying to mount my ext4 (sdc6) partition from a live usb because that's how I deleted two unused partitions left from a prior install of ubuntu, using GParted. The swap is mounted. However, I can't edit fstab, or find anywhere to click in nautilus to mount sdc6. In the terminal, I get the error: "can't find /dev/sdc6 in fstab". I'm afraid to exit the usb and update grub if that partition isn't mounted. Is there any easy way to do this, or do I have to install gksu or some other editor? Or do I need to mount it as sda6?  Device     Boot Start     End Sectors  Size Id Type /dev/sda1  *     2048 3905535 3903488  1.9G  b W95 FAT32  Device     Boot     Start        End   Sectors   Size Id Type /dev/sdc1            2048   29362175  29360128    14G 27 Hidden NTFS WinRE /dev/sdc2  *     29362176   29566975    204800   100M  7 HPFS/NTFS/exFAT /dev/sdc3        29566976  487023432 457456457 218.1G  7 HPFS/NTFS/exFAT /dev/sdc4       487024638 1250263039 763238402   364G  5 Extended /dev/sdc5       728393728  740290559  11896832   5.7G 82 Linux swap / Solaris /dev/sdc6       487024640  728391679 241367040 115.1G 83 Linux  Partition table entries are not in disk order. A Python module and package loading confusion