2 1-
()
, .
, (17)
p (x) q (x) .
q (x) = 0, (17) . , . 1.1.
q (x) ≠ 0, (17) . ( ) ( ).
,
, (18)
(17). , ,
,
.
, (18):
, (19)
.
(17) (19), , , ..
. (20)
() (20) (17):
,
.
, :
,
1 .
() (19), :
.
1.
.
. , () = 2 , q (x) = . .
1)
y ' + 2 xy = 0.
,
, .
2) .
,
y ', :
,
:
, (17)
y = u (x)× v (x), (21)
u (x) v (x) x, . .
(21):
.
(17) , :
;
.
, u (x), , u (x) . , ,
u (x) = .
. ,
.
, (17):
y = u (x)× v (x) = . (22)
|
|
2. .
. . ,
() = - 2/ , q (x) = .
.
y = u × v. : . :
.
, u , . , . , ( , - ).
v . . : . , .
,
y = uv = .
3. .
, . , v .
. , , .
R L
.
.
.
4. .
. L R . U t: U = f (t). . i t. , ,
. i , L
. ,
,
- .
,
,
, t = 0, ,
.
:
,
.
t , .
:
, :
, i ,
, , .
. , t .
.
y ' = p (x) ∙ y + q (x) ∙ ym, (24)
m ¹ 0, m ¹ 1, p (x) q (x) , .
, m = 0 (24) , . 1.4. m = 1 (24) ,
. 1.1.
(24) z = y 1- m ( ) y = u × v (.. ).
. .
|
|
. , () = 1/( - 1) = q (x),
m = 2. .
1- . . y = u × v.
:
.
':
.
, u ,
.
, .
, , ( , - ).
v , . ,
,
2- . . m = 2, , , , dy, :
.
:
, ,
, ,
.
, , ,
(x, y) + N(x, y) = 0
, (x, y) N (x, y)
. (25)
, F (x, y),
dF (x, y) = 0.
, , F (x, y) = .
, F (x, y),
dF (x, y) = (x, y) + N (x, y) . (26)
F (x, y). (7) (25), , (26).
, . (27)
(27), ( ):
, F (x, y) = .
(27):
= N (x, y).
ࠠ
.
, (), :
F (x, y) = ,
() .
(7) (27) . . : .
, ,
,
.
, , ,
,
.
1.
(y + ex sin y) dx + (x + ex cos y) dy = 0.
. , ..
(x, y) = y + ex sin y, N (x, y) = x + ex cos y,
= 1 + ex cos y.
= y + ex sin y.
:
F (x, y) = .
N (x, y):
= N (x, y);
= x + ex cos y.
' () = 0, () = 1. :
F (x, y) = ,
= 2 1.