Title: Equations and formulae
Course: UGQuants (SSPS) > Section: Maths Self Test

Equations and formulae

An equation is simply a series of numbers and/or other symbols, which contains an equals sign. An equation can be something as simple as 2+2 = 4.

Equations often use letters as well as or instead of numbers: e.g. a=b+c, where the letters stand for numbers or elements in the equation, which may or may not be known.

Equations sometimes use slightly different conventions with regard to simple arithmetical operations. E.g. axb (or a*b) is simply written ab; similarly a(b+c) means a multiplied by the sum of b and c (or ab+ac: the result is the same).

Division is usually indicated by a line dividing two numbers or combinations of numbers horizontally, similarly to a common fraction:$$ \frac{a+b}{c-d} \ = \ e $$ means the same as (a+b) ÷ (c-d) = e.

A useful tip to remember is that when we move any number or letter from one side of the = sign to the other, that number or letter changes its sign: + changes to – and ÷ changes to x (or *), and vice versa. So, e.g.a = b+c can also be written as b = a – c. e.g. if a = 4, b = 3 and c = 1, then 4 = 3 + 1 can also be written as 3 = 4 – 1.

A formula is really just another word for an equation, but we often talk about the formula for something. E.g. we could describe a = b + c as ‘the formula for a is b + c'.

This might sound a little abstract but will become clearer when you encounter actual formulae in the course.