-
 

                                                      

: "" "". .

: () a

() a

( |a|), : a 0, |a| = a, a < 0, |a| = -a. ., |3| = 3, |-5| = - (-5) = 5, |0| = 0. () z = x + iy (x y ) - +.

:

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" " (" ")
(Gambrinus)
(Bonn)