, .
.
, → , .. 2 1 2, 3 →1,2, 3, ..
, ( )
.
, , , , .
.
, , .. , . :
. .
, . M N , . , .
+ (x) +... + (x)y' + (x)y = f(x).
[a;b] y = Φ(x, C1,..., Cn), n C1,..., Cn :
− C1,..., Cn y = Φ(x, C1,..., Cn) [a; b];
− (x0, y0, ), x0∈ [a;b], C1 =C10,..., Cn = Cn0, y = Φ(x, C10,..., Cn0) y(x0) = y0, y '(x0) ,..., (x0) = .
( ).
[a;b], y1(x), y2(x),..., yn(x) ,
y(x,C1,..., Cn) = C1 y1(x) + C2 y2(x) +... + Cn yn(x) + y*(x),
C1,...,Cn , y*(x) .
2-
.
|
|
y" + py' + qy = f(x), q , f(x) , .
. . , .
y" + py' + qy = f(x).
1) F(x) = Pn(x), Pn() n. , Qn (x) , Pn (), r , .
. " 2' + = x+1.
: = (C1 + C2x). k2 2k + 1 = 0 (k1 = k2 = 1), , . , ' " , 2 + + = + 1.
: = 1, 2 + = 1, = 1, = 3. , = + 3, = x (1 + C2x) + + .
2) f(x) = eax Pn(x), n () n. , Qn(x) , n (), r , . = 0, f() = n (), . . 1.
.
(8)
.
(8) . (8): (9)
- (9), . :
) - . ;
) , , .. ,
) (k=abi), .
. 2-
[a; b]
+ (x) +... + (x)y' + (x)y = 0.
[a;b] y = Φ(x, C1,..., Cn), n C1,..., Cn :
− C1,..., Cn y = Φ(x, C1,..., Cn) [a; b];
− (x0, y0, ), x0∈ [a;b], C1 =C10,..., Cn = Cn0, y = Φ(x, C10,..., Cn0) y(x0) = y0, y '(x0) = y1,0,..., (x0) = .
( ).
[a;b], y1(x), y2(x),..., yn(x) ,
|
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y(x,C1,..., Cn) = C1 y1(x) + C2 y2(x) +... + Cn yn(x),
C1,...,Cn .