Åk 6–9
1.1 Introduction
When you look in a dictionary, you can find different definitions about equations. In order to explain in the easiest possible way, you can say that an equation:
  • is an equality between two mathematical expression, which are called the left hand side and the right hand side.
  • Contains one or several unknowns.  If it contains an unknown, we usually use the letter x.

5x + 2 = 18

The letter x is an unknown and 5x + 2 is equal to 18, it is an equality.

Formula and Equations
Many scientific and technical formulas can be expressed as equations.  One example is when calcultating the volume for a sphere (a ball is a sphere).

Foto: Specialpedagogiska institutet, Multimediabyrån

One of the most well known equation is Einstein’s
E = mc2 where he describes energy with mass.

Bild: Torben Freytag

We will go through more about formulas in the section Formulas and Functions.