8
, .. , , ( ).
n , , .
1, 2,..., n ; f 1, f 2,..., fn , , 1, 2,..., n, .
, , .
[ a, b ] n 1(), 2(),..., n (), , .
(1)
1 = 1(), 2 = 2(),..., n = n (),
:
, ,..., .
(1) n :
1, 2,..., n :
1) 1, 2,..., n ;
2) 1, 2,..., n (1) 1, 2,..., n.
, 1, 2,..., n.
: c n - :
y ( n ) = f (x, y, , ,..., y ( n - 1)),
, n - .
, ( ) .
ij (), fi () (i = 1,..., n; j = 1,..., n) .
fi () = 0, , .
ij () = ij = const, (2) .
. .
: n n . , , , n - .
|
|
1. :
. .
1. , y ' 1, y ' 2, y ' 3 .
.
y '' 1, y ' 1, y ' 2, y ' 3 :
, :
2 3:
2 3 :
:
.
1 = 10 + 1 *,
10 ;
1 *
2. 10 .
.
: k 1= 1, k 2= 2, k 3= 5 . ,
01 = 1 x + C 2 2 + 3 5.
3. 1 * .
(5) f (x) = 2
f 1(x) = f 2(x) = 2 , ,
1 * = 1 * 1 + 1 * 2, 1 * 1 1 * 2
.
f 1(x) = k = 1, f 2(x) = 2 k = 0, 1 * :
1 * = 1 x + 2 x + 3.
1, 2, 3. :
= 1 x + 1 + 2;
= 1 x + 2 1 ;
= 1 x + 3 1 .
, , 1 * (5):
1 x + 3 1 8( 1 x + 2 1 ) + 17( 1 x + 1 + 2) 10( 1 x + 2 x + 3) = 2 x.
:
4 1 + 17 2 10 2 x 10 3= 2 x.
, :
1= 1/4; 2= 1/5; 3= 17/50.
1 * :
1 * = x + x + .
4. , (5)
1 = 10 + 1 * = 1 x + C 2 2 + 3 5 + x + x + .
5. ' 1, '' 1:
' 1 = 1 x + 2 C 2 2 + 5 3 5 + x + + ;
'' 1 = 1 x + 4 C 2 2 + 25 3 5 + x + .
' 1, '' 1 (4):
= 1 x + 4 C 2 2 + 25 3 5 + x + 6( 1 x + 2 C 2 2 +
+ 5 3 5 + x + + ) + 6( 1 x + C 2 2 + 3 5 + x + x + ) + 2 x =
= 1 2 C 2 2 + 3 5 + x + x + ;
= 1 x + 4 C 2 2 + 25 3 5 + x + 5( 1 x + 2 C 2 2 +
+ 5 3 5 + x + + ) + 3( 1 x + C 2 2 + 3 5 + x + x + ) + x =
|
|
= 1 3 C 2 2 + 3 3 5 x x + + .
,
1= 1 x + C 2 2 + 3 5 + x + x + ;
2 = 1 x 2 C 2 2 + 3 5 + x + x + ;
3 = 1 x 3 C 2 2 + 33 5 x x + + .
(115):
1. | 2. | 3. |
4. | 5. | 6. |
7. | 8. | 9. |
10. | 11. | 12. |
13. | 14. | 15. |
(1618):
16.
17. x (0) = 1; y (0) = 1; z (0) = 0.
18.