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Git Gud's user avatar
Git Gud
  • Member for 11 years, 5 months
  • Last seen this week
126 votes

What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)

110 votes

Most ambiguous and inconsistent phrases and notations in maths

55 votes

Is $A + A^{-1}$ always invertible?

45 votes

Is $|1-i|$ larger than $|1|$?

37 votes

Prove $\sin^2\theta + \cos^2\theta = 1$

29 votes
Accepted

$-1 = 0$ by integration by parts of $\tan(x)$

26 votes
Accepted

How to prove that $\lim\limits_{x\to0}\frac{\tan x}x=1$?

26 votes

Prove that if $\sum{a_n}$ converges absolutely, then $\sum{a_n^2}$ converges absolutely

26 votes
Accepted

Show $\operatorname{rank}(A) + \operatorname{rank}(B) \ge \operatorname{rank}(A+B)$

24 votes
Accepted

Is $\mathbb Q(\sqrt{2},\sqrt{3},\sqrt{5})=\mathbb Q(\sqrt{2}+\sqrt{3}+\sqrt{5})$.

23 votes
Accepted

integrate $\int_0^{2\pi} e^{\cos \theta} \cos( \sin \theta) d\theta$

21 votes
Accepted

what does $|x-2| < 1$ mean?

21 votes

Sole minimal element: Why not also the minimum?

18 votes
Accepted

When is differentiating an equation valid?

17 votes
Accepted

Induction Proof that $x^n-y^n=(x-y)(x^{n-1}+x^{n-2}y+\ldots+xy^{n-2}+y^{n-1})$

16 votes

Why is it legitimate to solve the differential equation $\frac{dy}{dx}=\frac{y}{x}$ by taking $\int \frac{1}{y}\ dy=\int \frac{1}{x}\ dx$?

15 votes
Accepted

$A$ square matrix,nonsingular $\implies $ all submatrixes of $A$ are also nonsingular?

15 votes
Accepted

Solve $\sum nx^n$

15 votes
Accepted

How to solve $y''' - y = 2\sin(x)$

15 votes

What's your favorite proof accessible to a general audience?

14 votes

Are the integers closed under addition... really?

14 votes
Accepted

Relationship between Nilpotent Matrix and Matrix with all zero diagonal factors.

14 votes
Accepted

Interpretation of "not equal" notation

13 votes

Help with $\int\frac{1}{1+x^8}dx$

13 votes

Rigour in mathematics

13 votes
Accepted

Is $A^2=I \implies A=\pm I$ necessarily true?

12 votes

Another Epsilon-N Limit Proof Question

12 votes
Accepted

Prove that if $a$ is irrational then $\sqrt a$ is irrational

12 votes

Are continuous functions monotonic for very small ranges?

12 votes

$\lim_{x \to 0} \frac{e^{\sin2x}-e^{\sin x}}{x}$ without L'Hospital

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