MATHS - Algebra - Different Parts of an Equation

Expressions, equations, formulae and identities are all slightly different types of algebraic notation. In this video we’re going to discover the differences. An expression is a collection of letters and numbers, with no equals sign. An equation is two expressions that equal each other, and so can be solved. A formula is a special type of equation. It shows the relationship between different variables, like the area of a circle and the radius. A formula needs more than 1 variable - otherwise it is just an equation. An identity is another special type of equation. They are equations that are true no matter what values are chosen. The two sides of an identity are interchangeable, so we can replace one with the other at any time. Strictly speaking, for identities we should use the three bar sign which means “equivalent to”. But it is common to just see the normal equals sign.