Although the Greek mathematician and engineer Heron of Alexandria is noted as the first to present a calculation involving the square root of a negative number, it was See more

Geometrically, imaginary numbers are found on the vertical axis of the complex number plane, which allows them to be presented See more

• Nahin, Paul (1998). An Imaginary Tale: the Story of the Square Root of −1. Princeton: Princeton University Press. ISBN See more

• How can one show that imaginary numbers really do exist? – an article that discusses the existence of imaginary numbers.
• 5Numbers programme 4 BBC Radio 4 programme
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Care must be used when working with imaginary numbers that are expressed as the principal values of the square roots of negative numbers. For example, if x and y are both positive real numbers, the following chain of equalities appears reasonable at first … See more