What do I do with leftover egg whites? How long are they safe for?
How long can I store a food in the pantry, refrigerator, or freezer?
if $(x_0,y_0)$ is local extrema in $ax^2 + by^2 + cxy + dx + ey + l$ then its global too. An exercise on a book asks me to prove that if a point $(x_0,y_0)$ is a local extrema for the function $$f(x,y) = ax^2 + by^2 + cxy + dx + ey + l$$ then it's also a global extrema.  The exercise asks me to consider that $g(t) = f(x_0+ht,y_0+kt)$ is a parabola, but I couldn't understand how it helps. Maybe since it's a parabola, I know that this derivative has to be $0$ in some point, and also that this function $g(t)$ has a global extrema point, but I couldn't derive anything from this. I also tried to find the derivatives, equal them to $0$ and solve the system. I got:  $$x_0 = -\frac{2 b d - c e}{4 a b - c^2}, y_0 = -\frac{   c d - 2 a e}{-4 a b + c^2}$$  But when I try to find   $$f\left(-\frac{2 b d - c e}{4 a b - c^2},-\frac{   c d - 2 a e}{-4 a b + c^2}\right)$$ so I can try to prove:  $$f(x,y)-f(x_0,y_0)$$  is either greater or less $0$ depending on the case (so I can do $f(x,y) \le f(x_0,y_0)$ and $f(x,y) \ge f(x_0,y_0)$)  things get hairy. I'm taking a look at  (now removed), which all seem to be pretty much the same.  Should any be downvoted/flagged, and if so, which ones? I was using this:    To try and create numbered examples in my document.  However, when I load it and put the example exe in that link in one of the separate Tex files (Introduction.tex) I include in main.tex, I get:  ./Chapters/Introduction.tex:14: TeX capacity exceeded, sorry [parameter stack s ize=10000]. \gb@ifnextchar #1#2#3-&gt;                        \let \reserved@d =#1\def \reserved@a {#2}\def \reserv... l.14 ... and political news \cite{washington_post}                                                   .  More importantly, when ...   Which is not even referring to the exe example I inserted but a couple of blocks of tex above it.  For info, here is my full code before my document begins:  \documentclass{report} % [fontsize=11pt,border=5pt] % standalone for the tree \usepackage{forest} % This overrides warnings like http://tex.stackexchange.com/questions/52576/difference-between-bookmark-levels-greater-than-one-what-does-this-mean \usepackage{bookmark} \usepackage{amsmath} \usepackage{subcaption} \usepackage{standalone} \usepackage[round]{natbib} \usepackage[T1]{fontenc} \usepackage{lmodern} \usepackage[utf8]{inputenc} % This is for hyperlinks \usepackage{hyperref} \hypersetup{     colorlinks=true,     linkcolor=blue,     filecolor=magenta,           urlcolor=cyan, }  \urlstyle{same} % Not sure why I need to use this % \usepackage{graphicx} % \graphicspath{ {images/} } % \usepackage[pdftex]{graphicx} % fontsize=11pt,twoside]{scrartcl} % This is for numbered examples \usepackage{gb4e}   Would appreciate some help as I feel like my Latex is very messy here. How do I know if food left at room temperature is still safe to eat? If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more? When I create beamer frame, the content is centred in the slide. How do I make the content move to the top of the slide by default? What size images do I need for common print sizes, such as wallet size, 8x10, and 16x20?  Is there a general formula?  How could that size change if, for example, a 16x20 was printed on canvas rather than photopaper? If a function $f$ is continuous $\implies$ $|f|$ is continuous.(Answered by Myself) $(i)$ Given a function $f:E \rightarrow \mathbb{R}$ define $|f|:E \rightarrow \mathbb{R}$ by $|f|(x)=|f(x)|$ for $x \in E$ show if $f$ is continuous at $c \in E$ then so is $|f|$.        $(ii)$ Now the converse is not true, find $f$ such that $|f|$ is continuous but $f$ is not. Remove Background in Inkscape Indecomposable limit ordinals Since the Stack Exchange sites run on one clock, and a clock that is not common to most of us (such as those of us in the US), can we display a clock with the site time (UTC) displayed somewhere on every page, such as at the bottom with the other text?  That way we are more aware of when the days turn over, and ecetera...  close votes, delete votes, flags, and normal votes would also benefit from this as well (thanks @Grace Note!)...    What do you guys think? yea or nay? thoughts? How do I find my follower if and when they leave me? I had parked my follower at an inn with a bunch of valuable items that I didn't want to carry. I guess I have been out a bit too long as this message appears:      Your follower tires of waiting and leaves.    There have been other situations where my follower has mysteriously disappeared as well.  How can I find my follower when they get up and leave or disappear into thin air? Why Wi-Fi is getting turned-on automatically in iOS 11 TikZ: Bend text so that it follows a line I have two arrows going from a node on the left to a node on the right. Both arrows are slightly bent. I want to label the arrows with text that is bent just like the arrows. This is as far as I've got:  \begin{tikzpicture} \node (One) at (-3,0) [shape=circle,draw] {One};  \node (Two) at (3,0) [shape=circle,draw] {Two}; \draw [-&gt;, thick] (One) to [bend right=45]  (Two); \draw [-&gt;, thick] (One) to  [bend left=45] (Two); \node (mental) at (0,1.75) {Some bent text}; \node (non-mental) at (0,-1.75) {Some more bent text}; \end{tikzpicture} Why does Yoda speak the way he does? Yoda's unique speech consisting of reversed grammar is iconic.  Is there any reason he has adopted this speech pattern?  All other alien species encountered seem to have no trouble speaking normally. Why does Yoda speak in this way? I can't destroy blocks in Minecraft Creative Mode (singleplayer) The statement is: $f$ is a real fucntion on $\mathbb R$. Then if $f'(x)=f(x)$ and $f(0)=1$, then $f(x)\neq 0.$ Can a probability distribution value exceeding 1 be OK? How do I rename a domain and preserve SEO? As part of graduating from Area51 and becoming a full fledged site we sometimes change domain names from http://topic.stackexchange.com to http://example.com. Aside from the obvious 301 redirect rules to support existing urls transparently, are there other techniques that would aid in the preservation of SEO? releasing a second question concerning ordered stuff and set theory, which is very similar to my first question () which I'm putting here for reference.  The next problem that I'm stuck at in my book is this: we have an ordered triple $(a,b,c)$ and we want to define it using set theory. Why would $\{\{ a\} ,\{ a,b\} ,\{ a,b,c\}\}$ not work? The book requires from me to prove why it is not valid.  Additional info: I don't know how this matters but I'm gonna put it up anyhow. It is written within the book that the correct way to show it is $\{\{ a\} ,\{\{ a\} ,\{\{ b\} ,\{ b,c\}\}\}\}$  EDIT: Now, I consider that the correct case should matter. Besides pointing out why the first case is wrong I'm curious as to why the second one is correct Where is composition tab in QGIS Composer to change page size? I am trying to change the page size in the QGIS 3.0 Composer but I am not able to see the Composition tab.  I have right clicked an empty space in the toolbar but did not see anything about composition.  I am using Windows 7.  I tried looking at the QGIS docs but they are still in testing.