### Choose a topic

- Cryptography: A simple introduction into the world of ciphers and hash functions. Can you crack Caesar cipher?
- Elementary Mathematics: really basic stuff like integers, real numbers, sets, …
- Equations: how to solve equations like linear equation or quadratic equation.
- Functions: what is a function and how to draw a graph of a function.

### Article of the week… Quadratic Equation

A quadratic equation is any equation in the form

ax

^{2}+ bx + c = 0, where a, b, c ∈ ℝ and a≠0.The important part is the *ax ^{2}*. Every quadratic equation has to have this term and

*a ≠ 0*. Because if

*a = 0*then we can simplify the equation to

*bx + c = 0*and that’s actually a linear equation. The

*a*,

*b*and

*c*are real numbers and they are usually called

*quadratic coefficient*,

*linear coefficient*and

*constant*, respectively.

**…and you can read the rest on the dedicated page.**

### Other sources

If you haven’t found answers to your questions on this web, you can try other sources. When writing this web I usually draw knowledge from these websites or books:

- Khan Academy – there are infinite amount of high quality videos about mathematics. It’s kind of funny to hear the story how the Khan Academy has been founded, see Khan’s presentation on TEDx.
- Precalculus: With Unit Circle Trigonometry – this is a fantastic book. David Cohen knows his topic and can explain it well. And there are colorful pictures too! What more would you possible want from a math textbook?
- Calculus from Michael Spivak. As far as I know this is one of the most famous book about calculus ever written. If not the most famous.
- Wikipedia – I know, everyone knows Wikipedie so surprise here. Nevertheless is you want to know something about mathematics, it’s unlikely that you don’t find the answer on Wikipedia.

### Site map

Just choose an article and read it!