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 Apr 15 answered Using the slope from part (b), what is the equation of the tangent line to the curve at P? Jan 7 revised Stuck on integrating $\int x/(1-x)dx$ edited body Jan 7 revised Stuck on integrating $\int x/(1-x)dx$ typesetting Jan 7 suggested approved edit on Stuck on integrating $\int x/(1-x)dx$ Jan 7 answered Stuck on integrating $\int x/(1-x)dx$ Dec 28 comment How to show that show that $\frac{v+u}{1+ uv/c^2}=c$ when $u=c$? I'm guessing that you really mean $(u+v)/(1 + \frac{uv}{c^2})$, not $u+\left(v/(1 + \frac{uv}{c^2})\right)$. Dec 28 answered Why is $\cos(x/2)+2\sin(x/2)=\sqrt5 \sin(x/2+\tan^{-1}(1/2))$ true? Dec 26 answered Reference request: self-contained rigorous introductions to “cool” topics Dec 22 awarded Critic Dec 19 comment Finding the points of intersection of a circle and a line In Exercise 2, your two points do not satisfy $x + y - 1 = 0$. Dec 5 comment What is a simple example of an unprovable statement? Do you have a reference to this problem or ErdÅ‘s's paper? 5 minutes of Googling didn't turn it up, but that may be because your (nice) presentation of it isn't the canonical one. Oct 5 comment Expected deviation of a coin that obeys the gambler's fallacy My attempt to prove via induction that the variance is $\frac n {12}$ continues but is kind of in the weeds. Having that closed form of the probability of $h$ heads after $n$ flips couldn't hurt. The recurrence given on the Wikipedia page bears enough resemblance to the formula for $H(n)$ that I assume a proof that the probabilities are actually Eulerian is straightforward. Sep 30 comment Expected deviation of a coin that obeys the gambler's fallacy Calculation "by hand" (with a Python program) indicates that for $n \ge 3$, the variance is $\frac{n}{12}$ so the standard deviation is $\frac{1}{2\sqrt3}\sqrt n$. If I'm able to prove it (induction seems promising), I'll add the proof as an answer. Sep 30 awarded Explainer Sep 24 awarded Autobiographer Aug 27 comment A bag contains 4 balls. Two balls are drawn at random and are found to be white. What is the probability that all balls are white. If the book calls it "Baye's Theorem", I would not trust the book. Aug 5 revised Refining my knowledge of the imaginary number Corrected Chris Culter's anme Jun 4 comment 'Obvious' theorems that are actually false You order the rationals $q_1, q_2, \ldots, q_n, \ldots$ and place an interval of $(\frac \epsilon 2)^n$ around each one, choosing $\epsilon$ to be less than $1$. May 23 comment Are mathematical articles on Wikipedia reliable? I was curious whether Nature had a response to the response, and they did, here and here. (I have no contribution to make regarding which side is in the right; I'm just presenting the documents for others who are curious). May 1 comment Examples of mathematical results discovered “late” It took a surprisingly long time (17th century) for even very basic concepts of probability theory to be developed, considering that those concepts would have been immensely valuable in real life, given that gambling has been popular forever.