. ,
11 2 + 2 12 + 22 2 + 2 1 + 2 2 + = 0, (8)
11, 12, 22 .
11 2 + 2 12 + 22 2
, 2 1 + 2 2 , .
Ox ¢ y ¢,
x = a x ¢ + b y ¢ + b 1,
y = g x ¢ + d y ¢ + b 2.
(8), , .. x ¢ y ¢ . , . . , .
. O ¢ , . , , .
, , . M (x, y) M ¢( x, y). (7)
11 2 + 2 12 + 22 2 2 1 2 2 + = 0. (8¢)
(8) (8¢):
4( 1 + 2 ) = 0.
M (x, y) . 1 = 2 = 0, . , O ¢, , O ¢ ¢ ¢
11 ¢2 + 2 12 ¢ ¢ + 22 ¢2 + ¢ = 0, (9)
.. . , ; .
5. (x o, y o) , (8),
11 o + 12 o + 1 = 0,
12 o + 22 o + 2 = 0.
. O ¢ ¢ ¢, O O ¢(x o, y o) . :
x = x ¢ + o,
y = y ¢ + o.
(7):
11(x ¢+ o)2 + 2 12 (x ¢+ o)( y ¢+ y o) + 22(y ¢+ y o)2 +
+ 2 1(x ¢+ o) + 2 2(y ¢+ y o) + = 0.
11(x ¢)2 + 2 12 x ¢ y ¢+ 22(y ¢)2 + 2( 11 o+ 12 o+ 1) x ¢+
+ 2( 12 o+ 22 o+ 2) y ¢+ ¢= 0,
¢ = j(x o, y o) (7) O ¢. x ¢ y ¢ , (10).
, , (11) : , ¢.
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A = (8) ( (10)),
d = det A, dx = , dy = .
1 . d ¹ 0. (10)
x o= dx/d, y o= dy /d, (*)
. , 1 2 (10) , .
2 . d = 0, dx¹ 0 dy¹ 0 (, d = 0, dx dy ). (10) 2, rank A =1. , - (10) , .
3 . d = 0, dx = dy = 0. (10) , , , .
¢:
¢ = j(x o, y o) = 11 o2 + 2 12 o o + 22 o2 + 2 1 o + 2 2 o + =
= ( 11 o + 12 o + 1) o+ ( 12 o + 22 o + 2) o + 12 o + 22 o + .
(9) ,
¢ = 1 o + 2 o + . (12)
(*)
¢ = 1 + 2 + = ( 1dx + 2 dy + ) =, (13)
11 12 1
D = 12 22 2.
1 2
D . (13) (9) . , , ¢ (12).