Q&A #4927

Teachers' Lounge Discussion: Pre-calculus

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From: Loyd

To: Teacher2Teacher Public Discussion
Date: 2002050406:56:26
Subject: Re: jobs on imaginary numbers

On 2002011600:23:55, janine zesk wrote: > i would like to know what jobs use imaginary numbers in their work >and what formulas do they use to do their job? > Electrical engineers and physicists in particular use imaginary numbers. Complete understanding of motors and generators require the knowledge of imaginary numbers. Even the sine and cosine functions can be expressed in a complex form and this often permits solving problems in Calculus that is awkward and more difficult when you don't use them. Off the topic a bit, but all numbers are a subset of the complex numbers. For example, when you count, instead of saying 1,2,3,4,5, etc. You would be correct to say: 1+0i, 2+0i, 3+0i, etc., where 0i means 0 times i. Of course the latter would be cumbersome and that is a good reason not to do it that way. Nevertheless, it us useful to know that is the case. When you have a simple parabola which could be shaped like the cross section of a flashlight reflector, the real roots (or zeros) are where the curve crosses the x-axis. When the parabola has imaginary roots, the curve doesn't cross the x-axis and has imaginary roots. A theorem says that if you have 1 imaginary root, then there is at least two because imaginary roots only occur with their conjugate. I will stop before this gets more boring than it is.

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