For many years, mathematicians avoided using or thinking about the square root of negative numbers. Preferring to think in terms of real numbers, they simply agreed with each other that roots of negative numbers made no sense at all (for similar reasons, negative numbers were avoided for many centuries). After all, there is no physical length that can possibly equal such a number. What possible use or relevance could it have for our world?

The Italian mathematician Gerolamo Cardano (1501-1576) was the first to have explored complex numbers seriously. He used them in order to find solutions to cubic equations … and called them “fictitious.” Little did he realise what an incredible explosion of understanding would result from his first foray into this field!

It transpires that complex numbers are intimately connected with exponential equations and with trigonometry (see the image to the left, where i represents √(-1) and is called an “imaginary number”).

Nowadays, complex numbers are used whenever any repetitive, cyclic, or wave motion is being analysed (from star light to quantum mechanics to electric tuning circuits to shock waves during earthquakes)! Not only do mathematicians study them for the pure joy (and fascination) of the exercise, but they are used in many disciplines such as physics, chemistry, biology, engineering, statistics and economics.

Briefly, an imaginary number is one that is obtained by taking the square root of a negative number. If we define √(-1) as i (meaning *imaginary*), all imaginary numbers can be written as the product of i and some real number. This is because √(-k) = √(-1)⋅√k = i√k, where √k is real.

Complex numbers are hybrid numbers, obtained when we add a real number and an imaginary number together … such as 2 + 3i.

There is much, much more … so, watch this space!

I would describe Graeme as one of the best tutors I ever had. During my school years I spent some time attending one of the major tutoring organizations in town and I found it was difficult for the tutors to spend the time needed to assist me with problem solving due to the class size. My mother rang a private tutor in the phone book who gave her Graeme’s phone number as he specialized in tutoring high school students and was a teacher who used to work at my school. He offered a tutoring service at convenient times which suited our busy life style. The one-on-one service that Graeme provides was what I needed and I saw improvements straight away with my exam results. This made my parents very happy and I found a new confidence in approaching exams. I have since left school but have stayed in contact with Graeme and he has provided me with terrific practical suggestions in preparing for interviews. I would not hesitate in recommending Graeme as a great teacher.

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