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The Complex Numbers Numbers of the form z = x + yi, where x and y are real and i =  1art/squarerootofnegative1.gifthe square root of negative 1, such as 8 + 7 i (or 8 + 7  1art/squarerootofnegative1.gif times the square root of negative 1), are called complex numbers; x is called the real part of z and yi the imaginary part. The real numbers are thus complex numbers with y = 0; e.g., the real number 4 can be expressed as the complex number 4 + 0 i. The complex numbers are in a onetoone correspondence with the points of a plane, with one axis defining the real parts of the numbers and one axis defining the imaginary parts. Mathematicians have extended this concept even further, as in quaternions. Sections in this article:
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved. More on number The Complex Numbers from Fact Monster:
 number: The Complex Numbers  The Complex Numbers Numbers of the form z = x + yi, where x and y are real and i = , such as 8 + 7i ...
 complex number  complex number: complex number: see number.
 number  number number, entity describing the magnitude or position of a mathematical object or extensions ...
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