JLA's user avatar
JLA's user avatar
JLA's user avatar
JLA
  • Member for 11 years, 9 months
  • Last seen this week
72 votes
Accepted

Is there really no way to integrate $e^{-x^2}$?

13 votes

How are these two equal?

13 votes
Accepted

General misconception about $\sqrt x$

12 votes
Accepted

Why the unit circle in $\mathbf{R^2}$ has one dimension?

12 votes

Motivation of Weierstrass-approximation Theorem?

11 votes

Diagonalizable matrix $A$ invertible also?

9 votes
Accepted

Prove that $1, x, x^2, \dots , x^n$ are linearly independent in $C[-1,1]$

8 votes
Accepted

Finding two eigenvalues which add to $1$

8 votes

Zero Partials imply Constant Function Theorem or Proof

7 votes
Accepted

For monotonic $f$: if the improper integral $\int_0^\infty f(x)dx$ converges, then $\lim_{x\to \infty}xf(x)=0$

6 votes
Accepted

Show the closure of $\mathbb{Q}$ in $\mathbb{R}$ is $\mathbb{R}$.

6 votes

Is $\lim_{n \to \infty} \sqrt[n]{\frac{1}{n!}} = 0$?

5 votes

Range of $f(x) = \sin(\cos x)$

5 votes

Proving $\ln e = 1$

5 votes
Accepted

If the derivative is $0$, then $f$ is constant in a banach space

5 votes

Prove that $\mathbb{R}$ is not isometric to any proper subset of $\mathbb{R}$.

4 votes

Maximum Principle for a Poisson Equation?

4 votes

Prove that $AB=BA$ if $A, B$ are diagonal matrices

4 votes
Accepted

A "false" Lax-Milgram proof

4 votes
Accepted

For a convex function, the average value lies between $f((a+b)/2)$ and $(f(a) + f(b))/2$

4 votes

Convergence of $\sum \frac{a_n}{S_n ^{1 + \epsilon}}$ where $S_n = \sum_{i = 1} ^ n a_n$

4 votes

At $z=0$ the function $f(z)=\exp({z\over 1-\cos z})$ has

4 votes

What is the difference between the terms "classical solutions" and "smooth solutions" in the PDE theory?

4 votes

Prove $n!>n^2$ for $n>3$

3 votes

$\int_0^1|f_n|^3\leq 1\Rightarrow \int_E |f_n|<\varepsilon$ when $|E|$ is small

3 votes

Operator $X\mapsto AX$ has determinant $\det(A)^n$

3 votes

What would happen if infinity was treated like a number?

3 votes

Evaluating $\lim_{n\to \infty } \, \left(\sum _{k=1}^{\infty } \frac{1}{n}\right)$

3 votes
Accepted

Strange things happening with derivatives

3 votes

Integration and area - why is integrating over a single point zero?

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