Integral of $\tan(x)$
The easiest way to integrate $\tan(x)$ is to recall that $\tan(x) = \frac{\sin(x)}{\cos(x)}$. Do you see the necessary substitution? By choosing $y = \cos(x)$, that is, $dy = \sin(x)\,dx$ (...)
July 2, 2017 – Jakub Marian – Mathematics

Derivative of $x^x$
Calculating the derivative of $x^x$ is a very simple task, but it may be hard to find the general idea on your own, so here it is. We will (...)
July 2, 2017 – Jakub Marian – Mathematics

Integral of $x^n$
How to calculate the indefinite integral of $x^n$? It’s quite simple. We are looking for a function $f(x)$ such that $f’(x) = x^n$. As you (...)
July 2, 2017 – Jakub Marian – Mathematics

Integral of $e^{x^2}$ from $\infty$ to $\infty$
In this article, I will give a detailed explanation of why the Gaussian integral is equal to $√\pi$, that is, why the following equality (...)
June 29, 2017 – Jakub Marian – Mathematics

Number of Nobel laureates per capita in Europe (map)
The following map shows the number of Nobel laureates per 10 million inhabitants in European countries (the smaller caption shows the (...)
August 29, 2016 – Jakub Marian – Maps

I will send you one of my ebooks for free as a little gift.
The ‘day of the week boy or girl’ paradox explained
There is a wellknown result in probability theory that seems to defy common sense. Note that in the problem statement we assume that the (...)
July 25, 2016 – Jakub Marian – Mathematics

Labelling articles as “per capita” when the unit used is different
After I published my recent article about the Number of metal bands per capita in Europe, I got quite a few comments saying that my use of (...)
May 29, 2016 – Jakub Marian – Mathematics

The illusion of RGB screens
When an animal sees a computer screen, it doesn’t see the same colours as you do because our monitors only properly work for humans. This (...)

Difference between ‘violet’ and ‘purple’
People say that a picture is worth a thousand words, so let’s take a look at the two colours in comparison (there are various shades of (...)

What does it mean for a function to be welldefined?
A common addendum to a formula defining a function in mathematical texts is, “it remains to be shown that the function is well defined.” (...)
March 3, 2015 – Jakub Marian – Mathematics
