Question 1014818
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<pre>
a) all these points lie in the complex plane on the circle of the radius 5 with the center at the origin of coordinate system (z=0). 

    I will not plot them. Please do it yourself.


b) The geometric effect of multiplication by "i" is rotation in the angle {{{pi/2}}} (90 degrees) anti-clockwise.


c) The geometric meaning of {{{i^2}}} = -1 is in that the multiplication of complex numbers by "i" two times is the same 
    as rotation of the complex plane in angle {{{pi}}} (180 degrees) anti-clockwise.
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You may want to look into my lessons on complex numbers in this site

<A HREF=http://www.algebra.com/algebra/homework/complex/Review-of-lessons-on-complex-numbers.lesson>REVIEW of lessons on complex numbers</A>.