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!

Our daughter was tutored by Graeme as she was required to sit a maths exam, and complete a maths course, in order to attend college in the USA. Graeme came highly recommended as a brilliant tutor, and he definitely did not disappoint. As a parent of three adult children, I have accessed several tutors over the years, and none of them have come even close to being as helpful and skilful as Graeme. Our daughter, Michaela, particularly liked how Graeme could relate maths concepts to everyday situations, something that helped her immensely. Graeme has extensive knowledge in various areas of maths, and this knowledge combined with his patient, empathic manner, makes him the outstanding tutor that he is. Graeme went above and beyond what would be expected of a tutor. He was truly dedicated to our daughter’s learning and she could not have achieved her goals without him.

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