I am young...and dumb... so I want to ride fixed gear as all the other cool guys do. But without the trouble of having too high of a gear when starting away from a traffic light.  So is it possible to have a rear derailleur with a two- or three-speed cassette and one front gear, while still having a fixed-gear set up?  I thought of 48 in the front and something like 17-22-37 on the rear cassette?  Thanks in advance
Prompted by a  I was pondering the idea of bikes with variable gearing (derailleur or otherwise) but without the ability to freewheel. Have such bikes ever been widely used?  They would appear to share many of the advantages and disadvantages of fixies but be better at handling hills (up and down) while being more complex.
I remember seeing an upper bound for the binomial $\binom{n}{k}$ with an exponential function, something like $\binom{n}{k}\leq \left(ne/k\right)^k$. What exactly is it, and are there other similar good upper bounds for $\binom{n}{k}$?  Edit: As the link in Macavity's comment shows, the bound is indeed $\binom{n}{k}\leq \left(ne/k\right)^k$. How can we prove this? Evaluating $\int_0^{\large\frac{\pi}{4}} \log\left( \cos x\right) \, \mathrm{d}x $ I am having trouble with this problem from my latest homework.  Prove the arithmetic-geometric mean inequality. That is, for two positive real numbers $x,y$, we have $$ \sqrt{xy}≤ \frac{x+y}{2} .$$ Furthermore, equality occurs if and only if $x = y$.  Any and all help would be appreciated. I installed Ubuntu alongside Windows but I did not disable secure boot as someone told me it could cause problems with boot loader. So when installation finished and I rebooted, the system went straight into Windows. I went to Ubuntu IRC Support and they told me to turn off the secure boot and reinstall Ubuntu. I did that but my system still boot into windows.  This is a picture of partitions on my system:    This is my first Ubuntu install on my new laptop. I followed everdaylinux guide to install it and I used something else option. Series Summation,Convergence I am stuck on the 4 th one.I have done the rest.I have found out the value of a_n.But not getting how to proceed for the 4 th one. Can git be integrated with Xcode? Let $f:\mathbb R \to \mathbb R$ be a continuous function such that $f(f(f(x)))=x,\forall x \in \mathbb R$ , then is it true that $f(x)=x , \forall x \in \mathbb R$ ? I can see that $f$ is bijective , hence strictly monotone . But I cannot progress further . Please help. Thanks in advance How can I capture the movement of a bullet? Just beginning with photography.    Consider this image:     (This photo was taken by Harold "Doc" Edgerton in 1964 using his Rapatronic camera.)  I am looking for a  camera that can capture such an image. I am not looking for more fps. less fps is fine, but it must be able to capture such an instance.   What features should I look in such a camera?  How fast should be the shutter speed? What other things I should look for? $B^n/S^{n-1}$ is homeomorphic to $S^n$ Let $B^n$ be a n-dimensional disc (ball) with boundary $S^{n-1}$. Prove that  $B^n/S^{n-1}$ is homeomorphic to $S^n$.  Could someone check my proving, please?  Let  put the ball $B^n=\{x\in\mathbb R^n\mid |x|\leq 1\}$ into $\mathbb R^{n+1}$ using $x\mapsto (x,0)$. Then we can use homeomorphism $(x,0)\mapsto (x,\sqrt{1-|x|})$. We fall into the half of the sphere $S^n$. The boundary of the ball after this will turn just into points of the form $(*,0)$. If you pull it to the point then we will get suspension $S^{n-1}$ or $S^n$. What happened to the idea of getting inbox notifications for favorited questions? $\mathbb{Q}[x,y]/\langle x^2+y^2-1 \rangle$ is an integral domain, and its field of fractions is isomorphic to $\mathbb Q(t)$ I've noticed a MATCH SIMPLE and MATCH FULL, but I don't understand what they do. I see default is MATCH SIMPLE; but, how do the other MATCH clauses to the FOREIGN KEY constraint function? How should I transform non-negative data including zeros? If I have highly skewed positive data I often take logs. But what should I do with highly skewed non-negative data that include zeros? I have seen two transformations used:   $\log(x+1)$ which has the neat feature that 0 maps to 0. $\log(x+c)$ where c is either estimated or set to be some very small positive value.   Are there any other approaches? Are there any good reasons to prefer one approach over the others? Change to default start folder for Windows command prompt My new Windows XP work computer's command prompt automatically brings up "H:\&gt;" when I open it.  Is there a way for me to change that safely?  Specifically, to "C:\foo\bar\Something Else"?  I found the method of changing the Autorun value through Google, but it came with a warning that it "might affect the functionality of batch scripts."  Bonus note: I was originally getting at this issue in , but I didn't ask very directly.  The answer I ended up accepting was really good, so I wanted to leave it there. Prevent pdflatex from writing a bunch of files If I create just a basic hello.tex file an compile it using   pdflatex hello.tex   The pdflatex program is creating a plethora of file which is a little annoying. Currently it writes all those files about which I really don't care:  hello.aux, hello.log, hello.nav, hello.out, hello.snm, hello.toc   Is there a way to tell pdflatex to only write hello.pdf if the build is successful ? If not, can I specify the output directory of those files ? Maybe I could just write them in /tmp. Split a string by spaces -- preserving quoted substrings -- in Python I have a string which is like this:  this is "a test"   I'm trying to write something in Python to split it up by space while ignoring spaces within quotes. The result I'm looking for is:  ['this','is','a test']   PS. I know you are going to ask "what happens if there are quotes within the quotes, well, in my application, that will never happen. How to import a jar in Eclipse FAQ for Stack Exchange sites Community FAQ For sites in the Stack Exchange 2.0 network To see a list of commonly used words and phrases, see the . For official guidance from Stack Exchange, visit the . Asking questions                            Answering questions                 Accepting answers        Working with posts  What does it mean when a question or answer is...  ?  ?  ?  ?                                       Comments             Etiquette                         Promotion         Editing and Formatting                                    Tagging                      Reputation, badges, and voting                                         Moderation                                                 Searching and RSS feeds        Accounts, registration and logging in                                     Other                                 ()                                 Site-specific entries Stack Overflow             Meta Stack Exchange       Other     External links           Is your question not part of the FAQ? First look at questions tagged  to see if there is a question not in this index that might have the answer you seek. If you still can't find an answer, then see the following instructions for proposing an FAQ question. How can a question be added to this FAQ?  Ask only the question, stated plainly and simply, in the question body. The answer goes in an answer.  Link back to this index. Paste this at the end of the question:  [Return to FAQ index](/q/7931)   Tag as  and .  When a post seems to have hit a mature state, it will have  added by a moderator.  Flag for a moderator to mark community wiki.  Any FAQ post not yet community wiki should be made into a community wiki.  After the post has the  tag added to it, add a link in the above . "physical block size is 2048 bytes, but Linux says it is 512" when formatting USB - How to create a bootable USB without this error I was using:  dd  if=/path/to/my/ubuntuiso/ubuntu.iso  of=/dev/sdb1  bs=4M  &amp;&amp;  sync   In order to create bootable Ubuntu USB drives on older Ubuntu versions. It was working perfectly. Sometimes I used the Startup Disk Creator program, which  worked well.  But when I use the same methods on Ubuntu 16.04 LTS, I get some warnings while formatting it afterwards.   The installation media works as expected, but when I try to format that USB stick after my work is done, I get the following warning :    The partitioning of that Pendrive looks strange :    And it also shows my 16GB pendrive as 64GB.  After struggling a lot with Gparted, I will somehow format it. But Why is it happening like this ?? Is there any better methods of creating bootable Ubuntu in 16.04 ?  EDIT : there is a related question . But my question is not about how to format it properly. My question is "How to create a bootable USB without that errors." &amp; "Wht are the causes of that error" Ruby block and unparenthesized arguments I extracted simple example:  require 'pp' x = 1..3 pp x.map do |i| {:value =&gt; i, :double =&gt; (i*2)} end pp x.map { |i| {:value =&gt; i, :double =&gt; (i*2)} }  pp(x.map do |i| {:value =&gt; i, :double =&gt; (i*2)} end) pp(x.map { |i| {:value =&gt; i, :double =&gt; (i*2)} })   I am wondering why first pp produces:  [1, 2, 3]   While all the oders are giving:  [{:value=&gt;1, :double=&gt;2}, {:value=&gt;2, :double=&gt;4}, {:value=&gt;3, :double=&gt;6}]   I assume it has something to do with operator precedence. Where can I find good explanation?