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trisct's user avatar
trisct's user avatar
trisct
  • Member for 5 years
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66 votes
Accepted

What does "surface area of a sphere" actually mean (in terms of elementary school mathematics)?

41 votes
Accepted

Is there such thing as a "3-dimensional surface"?

17 votes

If the derivative of a function is square of it then it is constant

12 votes

Prove or disprove that there does not exist a monotone function $f:\mathbb{R}\rightarrow\mathbb{Q}$ which is onto.

11 votes
Accepted

Absolute convergence to a rational number

8 votes

Proof Verification $(\mathbb{Q},+)$ is not isomorphic to $(\mathbb{R}, +)$.

8 votes

Why doesn't substituting $u=\sqrt{x}$ help compute $\int_1^\infty\frac{\sqrt{x}}{x+1} \,\,\,dx$?

7 votes
Accepted

Can $\frac{\mathrm d}{\mathrm dx}$ increase the support of a function?

7 votes
Accepted

How to get a linear map with specified kernel and image

7 votes
Accepted

A nested double sum(to do with e?)

5 votes
Accepted

Find $\lim\limits_{x \to \infty}{\mathrm{e}^{-x}\int_{0}^{x}{f\left(y\right)\mathrm{e}^{y}\,\mathrm{d}y}}$

5 votes
Accepted

How to prove this interval related problem?

5 votes

Showing that $(\mathbb{R},+,\cdot)$ and $(\mathcal{M}_2(\mathbb{R}),+,\cdot)$ are not isomorphic rings

4 votes
Accepted

Finding rational solutions to $x^3+5y^3+25z^3-15xyz=0$, or proving that none exist

4 votes

Does there exist the inverse of $XX^T$?

4 votes
Accepted

What is the meaning of a matrix eigenvalue to be 0? (Singular matrix, I know but what about it?)

4 votes

Let $a_n \to 0$, then $\lim_{n \to \infty} (a_{n+1}-a_n)n $ equals to ??

4 votes
Accepted

Does $f(z)= \frac{z^5}{|z|^4} , \forall z \neq 0, ; f(0)=0$ satisfy Cauchy Riemann Equations?

3 votes
Accepted

Deriving the general form of the exterior product from the quotient space definition.

3 votes

What is the difference/relationship between the gradient and the Jacobian?

3 votes
Accepted

Questions about page 108-109 of Janusz's book Algebraic Number Fields

3 votes
Accepted

Exercise 3.14 (e) in Baby Rudin

3 votes

How to calculate $ \mathbb{Z}[x] /\langle2x-1\rangle $?

3 votes
Accepted

What is the meaning of $T$ in the power of a periodic signal

3 votes

How do we know $\sin$ and $\cos$ are the only solutions to $y'' = -y$?

3 votes
Accepted

If $\pi:X\to Y$ is a surjective local homeomorphism and $X$ is a smooth manifold, then does $Y$ become a smooth manifold?

3 votes
Accepted

Is $\mathbb{R}^{2} \times \{0\}$ an open set of $\mathbb{R}^{3}$?

3 votes

Is it possible for a Cauchy sequence to have no limit point at all?

3 votes
Accepted

What does orthonomality mean?

3 votes
Accepted

Distance from a point to a complement of a set