The Chaz 2.0
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 Jan 16 comment Help understanding what is asked of me Ducksauce, I'm almost certain it's in your book somewhere. What text are you using? (Or can you upload a scan of your notes?) Jan 16 comment All matrices which commute with all $2\times 2$ matrices @USB - for the sake of argument, how do you know that "this answer is correct"? Jan 15 comment The Sum Of Sets Or Intervals You're ignoring the context. $A$ and $B$ must be sets where addition ($+$) makes sense. So then the addition on the L.H.S. is really a new type, defined by adding (using the addition of $A,B$) elements of $A,B$. Jan 15 comment Breaking symmetries The link in the penultimate paragraph is dead ("inaccessible")... Jan 14 comment Finding a limit algebraically Lots of spoon-feeding going on in these answers! And yet nobody took the time to demonstrate the manipulation of the L.H.S... Jan 12 comment Combinatorics: Prove the number of matches in a Singles Tournament How is it obvious? Jan 8 reviewed Approve Why the answer to $\log(x+3)+\log(x+2)\geq \log 12$ different from that of $\log(x^2+5x+6)\geq \log12$? Jan 7 comment Determining the points of a rotated square. First line here: en.wikipedia.org/wiki/Rotation_matrix Dec 10 comment What does this summation notation denote? Well it's explained right there in the wikipedia page! The "sum" is really more like a successive adding, then subtracting, then adding, then... Dec 10 comment Evaluating $\frac{d}{dx}\int_{7-2x}^3 \frac{u^3}{1+u^2}du$ I'd switch the limits and (thereby) the sign... Dec 10 comment What is the difference between $\{1, 2\}\cup\{3\}$ and $\{1, 2, 3\}$? Right, and we "can" say $1=5$ or omit the differential in an integral, but we'd better keep it conventional for the elementary stuff. Dec 10 comment What is the difference between $\{1, 2\}\cup\{3\}$ and $\{1, 2, 3\}$? 0 is certainly not the appropriate symbol Dec 3 comment Suppose a, b, n ∈ N. Use the Euclidean algorithm to prove that gcd(na, nb) = n gcd(a, b) You didn't calculate (or mention) gcd(na, nb) at all... Dec 3 comment How can I prove $\sqrt{(111…)+(55…)^2}=5…6$ Square both sides and subtract? If the downvoter can't see that, I guess we're just going to have some downvotes. Dec 3 comment Explain why $|x^2-x|$ is not differentiable at $x=1$ I wouldn't say we "take off" the absolute value; we evaluate it. For the right-hand limit, the argument of the absolute value is positive (so yes, the | | goes away, in a sense). For the left-hand limit, the argument is negative, so we negate it when evaluating the absolute value. Dec 3 comment Proof: Characterize m (I mean stylistically - is it appropriate to demonstrate that it holds in two cases, and that it doesn't hold in the other three?) Dec 3 comment Proof: Characterize m Would it be sufficient to say that the statement holds, "iff m == a, b" and then just show ==> by inspection of a, b (which we know, but I'm being coy about), and then showing <== by inspection of the other three elements? Dec 2 comment Calculation of all positive integer $x$ for which $\displaystyle \lfloor \log_{2}(x) \rfloor = \lfloor \log_{3}(x) \rfloor \;,$ Most of my questions/answers on here were from an iPad as well, so I understand the struggle! A workaround is to click "edit" on the question, then copy+paste relevant code. A litte "\log_{2}" would go a long way in your answer (wrapped in dollar signs, of course). Dec 2 comment Calculation of all positive integer $x$ for which $\displaystyle \lfloor \log_{2}(x) \rfloor = \lfloor \log_{3}(x) \rfloor \;,$ You can/should right-click a mathematical expression to see its LaTex format: [Show math as] --> [Tex commands]. An example from this question is: \displaystyle \lfloor \log_{2}(x) \rfloor = \lfloor \log_{3}(x) \rfloor \; Dec 2 comment Proof: Characterize m Yes. What happens when you square $0,1,2,3,4$, mod 5?