any solutions or suggestions on this one?  An integer $n$ is called a $k$-th power if $n = m^k$ for some $m ∈ Z$. Show that if $n &gt; 1$ is not a $k$-th power, then its $k$-th root is irrational, i.e. not of the form $u/v$ for $u, v ∈ N$.
It is well known that $\sqrt{2}$ is irrational, and by modifying the proof (replacing 'even' with 'divisible by $3$'), one can prove that $\sqrt{3}$ is irrational, as well.  On the other hand, clearly $\sqrt{n^2} = n$ for any positive integer $n$.  It seems that any positive integer has a square root that is either an integer or irrational number.        How do we prove that if $a \in  \mathbb N$, then $\sqrt a$ is an integer or an irrational number?      I also notice that I can modify the proof that $\sqrt{2}$ is irrational to prove that $\sqrt[3]{2}, \sqrt[4]{2}, \cdots$ are all irrational.  This suggests we can extend the previous result to other radicals.        Can we extend 1? That is, can we show that for any $a, b \in \mathbb{N}$, $a^{1/b}$ is either an integer or irrational?
Is there any way other than instanceof operator for object type comparison in java? Show $GCD(a_1, a_2, a_3, \ldots , a_n)$ is the least positive integer that can be expressed in the form $a_1x_1+a_2x_2+ \ldots +a_nx_n$ Is there an efficient way to copy text from a PDF without the line breaks? How to run scripts every 5 seconds? How do I force TeX to completely use the 1st column before writing to the second column?  Right now I dont have enough content to fill one whole page. So the left and right columns are equally filled, leaving 25% symmetrical empty page at bottom. How do I fill the left column first, and then the right?  \documentclass{article}  \usepackage{multicol} \usepackage[scale=0.9]{geometry} \usepackage{amssymb} \renewcommand{\labelitemi}{\tiny$\blacksquare$} \begin{document} \begin{multicols}{2}      %lots of text goes here  \end{multicols} \end{document} What does the 'static' keyword do in a class? Why {are you / you are} making noise? I have this code:  DECLARE @MyTable AS TABLE (    [Month] INT,    Salary INT );  INSERT INTO @MyTable VALUES (1,2000), (1,3100);  SELECT [Month], Salary FROM @MyTable;   Output:    I want to concat the Salary (grouping by month) so that it will be NVARCHAR like this: '2000,3100'  How would I do this efficiently? I am using a Collection (a HashMap used indirectly by the JPA, it so happens), but apparently randomly the code throws a ConcurrentModificationException. What is causing it and how do I fix this problem? By using some synchronization, perhaps?  Here is the full stack-trace:  Exception in thread "pool-1-thread-1" java.util.ConcurrentModificationException         at java.util.HashMap$HashIterator.nextEntry(Unknown Source)         at java.util.HashMap$ValueIterator.next(Unknown Source)         at org.hibernate.collection.AbstractPersistentCollection$IteratorProxy.next(AbstractPersistentCollection.java:555)         at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:296)         at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:242)         at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:219)         at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)         at org.hibernate.engine.Cascade.cascade(Cascade.java:130) Do I need a RHEL subscription to install packages? Random integer in VB.NET I need to generate a random integer between 1 and n (where n is a positive whole number) to use for a unit test. I don't need something overly complicated to ensure true randomness - just an old-fashioned random number.  How would I do that? During Thor's interrogation, Agent Coulson exits the room and Loki enters and informs him that his father Odin had passed away and that he cannot undo his banishment. Not only does he communicate with Thor, but he goes to the area where Mjölnir is embedded in the rock and attempts to lift it, with SHIELD scientists and agents completely oblivious to his presence. Loki shows a similar ability when he converses with 'The Other' and when he manipulates Erik Selvig. Is this a part of Loki's illusion powers or another one of his abilities that has not been addressed? How was he able to visit Earth without using the Bifrost? Dividing polynomial $f(x)$ by $x-3$ and $x+6$ leaves respective remainders $7$ and $22$. What's the remainder upon dividing by $(x-3)(x+6)$? How to Start Web Mapping? find command with regex quantifier e.g. {1,2} I have been trying to create a find command string that will find all files that end with a number 1-99 but exclude all others.  e.g. I want to find myfile1 myfile99 but not myfile456 and not myfilebackup  The regex I'm thinking of is myfile[1-9]{1,2} but I can't get this to work with find.  find . -regex '.*myfile[0-9]{1,2}' OR  find . -iname 'myfile[0-9]{1,2}'  From what I can see it's the {1,2} part that is not working.  (by the way can you use -name -regex interchangably?)  Any help appreciated. Is there a human home planet? Did all the humans in the Star Wars universe originate on a single planet some time in the distant past, or did they originate on different worlds and intermix into one species over millenia?  This is specifically about only humans, not humanoid aliens. I would prefer answers from the main canon or EU canon. It is easily checked that $\displaystyle\sum_{i\ =\ 0}^{n}\left(\, -1\,\right)^{i} \binom{n}{i} = 0$, for example by appealing to the binomial theorem.  I'm trying to figure out what happens with the truncated sum $\displaystyle\sum_{i\ =\ 0}^{D}\left(\, -1\,\right)^{i}\binom{n}{i}$.  How far away from $0$ can this get, as a function of $D$ ?.  I'm mostly interested in the case of when $D \ll n$, such as $D \sim \,\sqrt{\,n\,}\,$.  Thanks ! Windows 7 Automatic Log-on with a Default User Account? I have two User Accounts for my Windows 7 with no password requirement. I frequently use one of those accounts; so I would like Windows to log-on automatically with that account without the need for user input.  P.S. I don't prefer installing/using a third-party software for that purpose; especially those that place at low levels before Windows log-on. How can I add custom '.desktop' application launchers to Ubuntu Dock? Name of short sci-fi story involving a musician who is punished for listening to Bach