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bio website anhhuy.ch
location Switzerland
age 22
visits member for 4 years, 2 months
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My name is Anh Huy Truong and I am currently studying mathematics at the ETH Zürich.


Jan
1
comment A simple proof that $\bigl(1+\frac1n\bigr)^n\leq3-\frac1n$?
By multiplying both sides of the second last inequality with $n(n-1)$, we get $-3(n-1) - n + 1 \leq -(n-1)$ which is equivalent to $-3n + 3 - n + 1 \leq -n + 1$, and by adding $3n-3$ to both sides, I ended up with $-n+1 \leq 2n-2$, if you're wondering. It seems simpler to just add $n-1$ to both sides, to retrieve $n \geq 1$ immediately. I changed the answer accordingly.
Jan
1
comment A simple proof that $\bigl(1+\frac1n\bigr)^n\leq3-\frac1n$?
Also, your last line implies that $\frac{3}{n+1} \leq 0$, which is wrong.
Jan
1
comment A simple proof that $\bigl(1+\frac1n\bigr)^n\leq3-\frac1n$?
You have a mistake in your calculations. Note that $$- \frac{n+1}{n(n+1)} - \frac{1}{n(n+1)} = \frac{-n-1-1}{n(n+1)} = -\frac{n+2}{n(n+1)}.$$
Jan
1
answered A simple proof that $\bigl(1+\frac1n\bigr)^n\leq3-\frac1n$?
Jan
1
revised Diagonalization versus s.d. product for non-commuting Hermitian matrices
added 112 characters in body; edited tags
Jan
1
comment Function and sequence
How do you get $u_0 > u_1$ in question 5?
Jan
1
comment Conversion of the Gauss law $\nabla \cdot E = \frac{\rho } {\epsilon_0}$ into integral form
Basically, you're going back from Maxwell's first equation $\nabla \cdot E = \frac{\rho}{\epsilon_0}$ to Gauss' law $\Phi_E = \frac{Q}{\epsilon_0}$. As Siminore has pointed out, your notation is a bit problematic.
Jan
1
reviewed Approve Eigenvectors of $2\times 2$ real symmetric matrix
Jan
1
comment Cauchy product of two different series
What did you try?
Jan
1
revised What is $\rightarrowtail$ used for?
edited tags
Jan
1
revised Diagonalization versus s.d. product for non-commuting Hermitian matrices
deleted 9 characters in body
Jan
1
comment What is $\rightarrowtail$ used for?
Knowing a map is an injection is often better than only knowing it is a map. See: en.wikipedia.org/wiki/Injective_function
Jan
1
answered What is $\rightarrowtail$ used for?
Jan
1
answered Diagonalization versus s.d. product for non-commuting Hermitian matrices
Jan
1
revised Forming contrapositive
edited tags
Jan
1
revised Forming contrapositive
added 319 characters in body
Jan
1
answered Forming contrapositive
Dec
31
reviewed Approve Is the complement of an open ball in a Banach space connected?
Dec
31
answered Non-zero eigenvalues of $AA^T$ and $A^TA$
Dec
31
answered help on a specific power series expansion, i cannot see what the author did here