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16h
comment Can 720! be written as the difference of two positive integer powers of 3?
Thanks for the explanation. This was a really nice solution!
17h
comment Can 720! be written as the difference of two positive integer powers of 3?
Can you please explain the first congruence? I don't see where the $2^k$ came from
1d
answered Finding the minimal polynomial of a linear operator
2d
comment Is it possible to embed $\mathbb Z^n$ inside $ \mathbb Z^m$ as a $\mathbb Z$-module for $m < n$?
What exactly do you mean by linearly independent where we arn't talking about vector spaces ?
Aug
19
answered Prove that $\lim _{x \to \infty} \sin x$ doesn't exist (using delta epsilon)
Aug
18
answered G's order is a multiply of coprime numbers, need to prove about its subgroups.
Aug
15
answered True or false. If A ∪ B = ∅ , then A = ∅ and B = ∅ .
Aug
12
comment Mental Calculations
And given that the answer was probably an integer given the nature of the question, this really solved it the way I see it
Aug
10
comment Geometric or at least application view of a group with 3 elements?
How about rotation by 120 degrees?
Aug
7
answered Showing irreducibility of a polynomial.
Aug
7
comment $\sum_{n=1}^\infty a_n = \sum_{n=1}^\infty n a_n$ possible?
This assumes that the series is a positive series?
Jul
26
comment How is the Fourier transform a geneeralization the the Fourier series?
@Mitsos - seems that I forgot the $n$, should be ok now
Jul
26
revised How is the Fourier transform a geneeralization the the Fourier series?
edited body
Jul
26
asked How is the Fourier transform a geneeralization the the Fourier series?
Jul
24
comment Notation of an infinite union
@vadim123 - whoops, I saw to many [infinite] sums this week :P
Jul
24
revised Notation of an infinite union
deleted 216 characters in body
Jul
24
answered Notation of an infinite union
Jul
22
comment How prove : polynomial $P(x)=W^{\prime \prime}(x) +(W^\prime(x))^2$ have a real root.
How did you came up with this? What's the motivation?
Jul
17
comment For which integers $r$ is $\sigma ^r$ also a $k$-cycle?
You should at least describe your proof so someone won't repeat it
Jul
16
answered If $a^n=e$ for exactly one $a$ then show that $a\in Z(G)$