Description:
the definition of the derivative, a simple useful concept which became the core of mathematical analysis, and later became so useful in many other fields
Description:
the first and most basic idea of economics, everything is ruled by supply and demand, that's why I have an economics joke, but there is no demand
Description:
the first and most basic idea of economics, everything is ruled by supply and demand, that's why I have an economics joke, but there is no demand