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Jul
21
comment a GRE question about ring theory, how can I know which one is correct?
This and @DerekHolt information should be enough to answer the question.
Jul
21
comment a GRE question about ring theory, how can I know which one is correct?
$\{0\}$ and $R$ are ideals for every ring $R$.
Jul
11
comment Proving linearity of derivative
It must be a linear function. Otherwise, the linear approximation formula doesn't make any sense.
Jun
18
comment Math Problem Help || Trig (Updated picture)
This hurts my eyes.
Jun
18
comment Palindromic numbers, and $3$.
Nothing about this question makes sense.
Jun
18
comment Palindromic numbers, and $3$.
Even more furthermore, if $x$ is a palindromic number, it's still not true :p
Jun
18
comment Palindromic numbers, and $3$.
Did you mean to apply this to palindromic numbers?
Jun
18
answered Palindromic numbers, and $3$.
May
11
comment How to find the maximum value subject to constraints
This is definitely in either your textbook or class.
Apr
18
comment Continuity of integral from x to x+1 of Lp function
Hint : Holder .
Mar
24
comment Wave equation in three space dimensions
The dot just means the $x$ variable. As you can see, the estimate only depends on the $t$ slice.
Mar
8
comment How do none of the of the polynomials have a degree 2?
It is definitely wrong because $x^2$ is a degree 2 polynomial!
Mar
6
comment How to handle derivative of absolute value?
Please look up the definition of weak derivative. The function might have a derivative in this sense.
Mar
6
comment Two norms $||.||_1$ and $||.||_2$ on a vector space $V$ are equivalent.
This question has been answered at least 50 times on this site.
Mar
6
comment Find the limit of $\lim\limits_{x\rightarrow0}\frac{x}{\tan x}$.
It was wrong. Now it's correct.
Mar
6
comment Find the limit of $\lim\limits_{x\rightarrow0}\frac{x}{\tan x}$.
False? ${}{}{}{}$
Mar
6
comment What decides if a Coxeter Group is “crystalline” or “non-crystalline”?
This is going to be very hard to completely intractable depending on how much math you know. Do you know any group theory? Have you read the wikipedia article on Coxeter groups? It might be a little easier to read as an introduction than a paper.
Feb
27
comment About a theorem on stability of sytems of autonomous ODEs
Is that word for word what the theorem says? It seems to be wrong then by your counterexample.
Feb
27
comment Solve 2nd order ordinary differential equation by Laplace transforms and convolution of their inverse functions. (5.6-40)
Not correct. You can easily check by plugging it into your original equation.
Feb
26
comment How to solve $tx'(t) = (2t^2 + 1)x(t) + t^2$?
This seems to be a simple 1d problem that you can solve with an integrating factor.