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David Z's user avatar
David Z's user avatar
David Z's user avatar
David Z
  • Member for 13 years, 11 months
  • Last seen this week
62 votes

Why do we still do symbolic math?

24 votes

% of % - Please Help Me Prove My Friend Wrong

21 votes

What's so special about sine? (Concerning $y'' = -y$)

14 votes

What does .9 with a line above the 9 mean?

11 votes

How to prove that perpendicular from right angled vertex to the hypotenuse is at most half the length of hypotenuse of a right triangle?

7 votes
Accepted

Where do the first two numbers of Fibonacci Sequence come from?

6 votes

Simple proof of irrationality of e

6 votes
Accepted

How to use a derivative

5 votes

How to prove $\exp(x)/(\exp(x)+1)^2$ is even?

4 votes

Connection between cross product and determinant

4 votes

Why Can't $\delta$ depend on $x$ in $\delta-\epsilon$ Proofs

4 votes

Multiplying both sides of an equation when there's a limit on one side?

4 votes

Sum of a geometric series whose common ratio might be 1

4 votes

How useful/useless is the indefinite integral

4 votes

Why does something constant have a parabolic shape?

4 votes

Is there a continuous Taylor/MacLaurin transform (like the Fourier transform)?

3 votes

Blow up of a solution

3 votes

Why do oscillating sequences diverge?

2 votes

Indefinite integral of a simple function

2 votes

Can someone provide the formal definition of the tangent line to a curve?

2 votes

Partial differentiation of double integrals.

2 votes

Given 5 equations, can I solve for 6 unknowns?

2 votes
Accepted

Rearrange $y = x\tan y$ to solve for $y$ given $x$

2 votes

Express $I_{n}(x)=\int (x^{2}+1)^{(n-0.5)} dx$ with recursion

2 votes

Is the limit of $f(n) = n-n$ zero as $n\rightarrow \infty$?

2 votes

How to evaluate $ \frac{1}{3} + \frac{2}{3^{2} } + \frac{1}{3^{3}} + \frac{2}{3^{4}} + \frac{1}{3^{5}} + ...$?

1 vote

How do I show $\sqrt{n} \not \in O(\log{n})$?

1 vote

Can you add an extra $e^x$ when integrating?

1 vote

Help Understanding Spectral Method for solving Differential Equations

1 vote
Accepted

Finding the spectrum of the Schrodinger operator