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 Yearling
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Dec
23
awarded  Yearling
Sep
27
answered Property of a spanning list in a finite-dimensional vector space
Sep
20
revised Solving a generic second order differential equation
added 5 characters in body
Sep
19
answered Solving a generic second order differential equation
Sep
15
answered First class example and i have no clue what to do
Sep
15
revised First class example and i have no clue what to do
added 67 characters in body
Sep
15
comment A simple question about ring theory
@JohnLee $$x+y=(x+y)^2\\x+y=x^2+y^2+xy+yx\\x+y=x+y+xy+yx\\xy+yx=0$$
Sep
9
comment What is a moving average system?
@Guesswhoitis. the OP is a causal filter, yours is not. the way to see how this works is to consider a sliding window of 3 samples and at each point, the output $y[n]$ is the mean of the previous 3 input samples $x[n],x[n-1],x[n-2]$ in the window
Sep
9
revised Definition of characteristic polynomial
edited body
Sep
1
answered Change of variable using dirac delta function
Sep
1
comment Proving $[(P\lor Q)\land(P\to R)\land(Q\to R)]\to R$ is a tautology without using a truth table?
what inference rules do you have? surely implication elimination, i.e. $(a\rightarrow b)\land a\implies b$
Sep
1
comment Find $\sum\limits_{n=1}^{\infty}\frac{n^4}{4^n}$
Fourier series instead of generating functions -- nice
Sep
1
comment Understanding Little Oh Notation Proof - Prove the function$ f(n) = 12n^2 + 6n\ \ is\ \ o(n^3)$
if for any $c$ we can find $n_0$ such that $0\le f(n)\le cg(n)$ holds for $n\ge n_0$ then it follows that $n\ge n_0$ is sufficient to give a strict bound $0\le f(n)<dg(n)$ for $d>c$. So if we want to show for $d$ that there is $n_0$ so that $0\le f(n)< dg(n)$ for $n\ge n_0$, just pick a $c$ such that $0<c<d$ (e.g. $c=d/2$) and $n_0=\frac{18}c=\frac{36}d$ will work for the strict inequality in $d$.
Sep
1
answered Find $\sum\limits_{n=1}^{\infty}\frac{n^4}{4^n}$
Sep
1
answered Understanding Little Oh Notation Proof - Prove the function$ f(n) = 12n^2 + 6n\ \ is\ \ o(n^3)$
Aug
30
comment Showing for any real number $\lfloor a\rfloor+1>a$
how are you defining $\lfloor a\rfloor$? once you specifically have that it should be obvious
Aug
30
comment Generalizing limits of sums, products, and quotients of sequences to abstract topological spaces?
@EthanAlvaree en.wikipedia.org/wiki/Algebra_over_a_field
Aug
22
comment Polynomial equations of degree larger than 4
finding cube roots is trivial by de Moivre's theorem: $z^3=re^{it}$ gives $z\in\{\sqrt[3]{r}e^{it/3},\sqrt[3]{r}e^{i(t+2\pi)/3},\sqrt[3]{r}e^{i(t+4\pi)/3}‌​\}$
Jul
31
comment Asymptotic direction
just an fyi: the second derivative doesn't live in the tangent space or bundle
Jul
31
comment Proof that the Runge Phenomenon occurs
the reason is given right here