, (1), tr A det A.
1. , :
2. , :
3. .
4. , .
5. , , , .
6. .
7. , .
, . , .
, , , .
y = kx. y = k x :
k :
(4) |
( , , x = ky.
(4).
* x = ky, x = k 1 y y = 0.
, .
, .
, , , :
a x + b y = C .
, ( ) ( ).
, (), . , , . y ′(t) x.
x > 0, .
|
|
() .
x > 0, () .
, ( ) , () .
, , - . .
()
, :
1
, . .
2
, . , y = k 1 x :
x (t) → 0 t → +∞, y = k 1 x .
x (t) → ∞ t →+∞, .
3
x , x.
x > 0, , , , x, . , .
, y, .
4
1.
1. ,
det A = 6 ≠ 0.
2. l2 6 = 0, l1,2 = Ö6. . , .
, , eig.
>> a=[-2 -2;-1 2];
>> eig(a)
ans =
-2.4495
2.4495
3. y = kx.
4. : x + y = 0.
: x + 2 y = 0.
2.
1. , det A = 10 ≠ 0.
2. l2 + 7l + 10 = 0,
l1 = 2, l2 = 5. , .
>> a=[4 2;1 3];
>> eig(a)
ans =
3. : y = kx.
4. : 2 x + y = 0.
: x + 3 y = 0.
:
>> A=[4 2;1 3];
>> [U,L]=eig(A)
U =
0.8944 -0.7071
0.4472 0.7071
L =
5 0
0 2
.., l1 = 5 l2 = 2.
l2 = 2 , :
|
|
>> U(:,2)./0.7071
ans =
-1.0000
1.0000
, , , y = x.
.
3.
1. , det A = 18 ≠ 0.
2. l2 + 3l + 18 = 0,
D = 63. D < 0, , Re l1,2 = 3/2. , .
>> a=[-1 -4;4 -2];
>> eig(a)
ans =
-1.5000 + 3.9686i
-1.5000 - 3.9686i
3. : x + 4 y = 0.
: 2 x y = 0.
, . .
y ′(t) x. y = 0 :
x > 0.
, x .
, .
4.
1. , det A = 3 ≠ 0.
2. l2+3 = 0, l1,2 = i Ö3. , .
>> a=[1 -4;1 -1];
>> eig(a)
ans =
-0.0000 + 1.7321i
-0.0000 1.7321i
3. : x 4 y = 0.
: x y = 0.
.
, , .
y ′(t) x. y = 0 :
x > 0.
, x .
, .
5.
det A = 0, . y = 2x.
l2 + 5l = 0,
l1=0, l2= 5.
>> a=[-4 2;2 -1];
>> eig(a)
ans =
-5
, .
:
,
6.
det A = 0, . y = 2 x.
tr A =0, l1 = l2 = 0.
>> a=[2 -1;4 -2];
>> eig(a)
ans =
1.0e-015 *
0.0650 + 0.3140i
0.0650 - 0.3140i
, .
:
, y = 2 x + C, C const, .
.
y ′(t) x. y = 0 :
, x , .
, , .