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, (XVI):
x 2+4 x +13=0 D 1= 4 -13=-9.
, . .
z =x+iy, x y , i , : i 2 = -1.
z 1 = (2+3 i), z 2 = (2-3 i).
y , , z :
x = Re z, y = Im z
y = 0, z = x + i 0 x. x = 0, z = 0 + i y i y .
(x,y) .
z = x + iy z (x,y) , , z = x + iy.
, .
(z). O. O . z = iy O, .
.1.
1.2.
1. :
z = x + iy. (1)
z 1 = x 1 + iy 1 z 2 = x 2 + iy 2 (z 1 = z 2) ,
x 1 = x 2, y 1 = y 2
x 2 = x 1, y 2 = - y 1, z1 = z2 :
z = x + iy, = x i y.
z (x,y) z (x,-y) O.
2. .
- z φ, O. (.1).
r φ , , z :
r = | z |; φ = Arg z.
( , 1);
r = | r |
φ
,
φ z:
, , 2 π. z =0, .
Arg z :
, x > 0, y > 0;
- , x < 0, y > 0;
|
|
Arctg z =
+ , x < 0, y < 0;
2 - , x > 0, y < 0;
. :
: x = cos φ y = sin φ. :
( = r)
(2)
z 1 z 2 , , 2 π:
;
(1) (2) :
; ..
: -
.2.
3. .
. :
= cos φ - i - ( ) (3)
. (2) :
(4)
: .
(3) , 1:
|
.
. 3.
φ =0 z = =1; φ=π /2 z= =I .. , φ 0 2 π z = .
, T = 2 π.