Gerry Myerson
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123,079
99/100 score
 Aug 27 comment Factor $x^5 + x + 1$ I have no idea what the $2x-x$ is supposed to do for you. But you can get some mileage out of adding and subtracting $x^2$, that is, writing $(x^5-x^2)+(x^2+x+1)$. Aug 27 comment Finding $P$ Such that $D=P^TH\overline P$ What do $L^{-*}$ and $L^{-T}$ mean? Aug 27 comment Find the coefficients($x^{15}$,$x^{11}$) of the function $(2x^2-\frac{3}{x})^{10}$ OP labeled it "homework", and asked for "advice how to continue". OP will not now have the pleasure of working out the solution. Aug 27 revised Calculate the sum of the following series typo in title Aug 27 comment Calculate the sum of the following series Hint: The Binomial Theorem. Aug 27 comment Find the coefficients($x^{15}$,$x^{11}$) of the function $(2x^2-\frac{3}{x})^{10}$ If that's what you call a hint, what do you call a complete answer? Aug 27 comment $a,b,c>0,a+b+c=21$ prove that $a+\sqrt{ab} +\sqrt[3]{abc} \leq 28$ Equality, by the way, is obtained when $a=16$, $b=4$, $c=1$. Aug 27 comment $a,b,c>0,a+b+c=21$ prove that $a+\sqrt{ab} +\sqrt[3]{abc} \leq 28$ Source of the problem, please? Aug 27 awarded Enlightened Aug 27 comment Why some functions are not integrable? No, Banach-Tarski only comes up in higher dimensions, non-integrability already comes up in one dimension. Aug 27 comment Why some functions are not integrable? It's not easy to explain this without invoking some high-powered stuff. One can find a non-measureable subset of the interval $[0,1]$. Then the function that is 1 on that set and zero elsewhere won't be integrable. Aug 27 revised Would the answer of the square root of a square root be positive or negative? typos Aug 27 awarded Nice Answer Aug 27 answered $1^k+2^k+\cdots+n^k\mod n$ where $n=p^a$. Aug 27 answered How can we prove that the sum of all elements of $A^{\displaystyle-1}$ is $5$? Aug 27 revised How can we prove that the sum of all elements of $A^{\displaystyle-1}$ is $5$? typo in title Aug 27 comment A question regarding a step in power method justification (Writing a vector in terms of the eigenvectors of a matrix) "the proof of the power method" Which proof? In which book/paper/website/t-shirt? Aug 27 comment Solution to Linear Nonhomogeneous Differential Equation If you want to get someone's attention, you have to put @ before the name. Aug 27 comment Calculating all minimal generators of a finite group Note, by the way, that if $p$ is a large prime, then there is no known efficient way to find even one minimal generating set of the multiplicative group modulo $p$, even though it's known that the group is cyclic. Aug 27 comment Calculating all minimal generators of a finite group Of course there is a way to calculate all minimal generating sets of a given finite group; test every subset of the group to see whether it is a generating set, starting with the 1-element subsets, then the 2-element subsets, etc. You might want to refine the question.