n- - -, -
a0(x)y(n)+a1(x)y(n-1)++an-1(x)y+an(x)y=φ(x)|: a0(x)
φ(x)=0-
φ(x)≠0-
y(n)+p1(x)y(n-1)++pn-1(x)y+pn(x)y=g(x)- (1) -
:
* y1- , y1, - -.
* y1+ y2 -.
10 - y1, y2,, ym - -.
* (1) pi(x)∈R y(x)=u(x)+iv(x), Rey=u(x) Imy=v(x) -.
- y1(x), y2(x),, yn(x) (a,b), a1,a2,,an≠0 , x (a,b) a1 y1(x)+a2 y2(x)++an-1(x)y+an yn(x)=0. - ., .
a1=a2==an=0, - y1(x), y2(x),, yn(x) (a,b).
* - y1(x), y2(x),, yn(x) (a,b), (. )
W(x)=W[y1, y2,, yn]= =0 .
:
* - y1(x), y2(x),, yn(x) (1) (a,b) pi(x), (a,b) = 0.
(1) (a,b) pi(x) (i=1,2,,n) y= n yi .
10 .
- n - n- .
*yo=yoo+y
. n- .
. , , . , .. , - . - 1() 2()
=+
.
44*. . . ( ).
|
|
y'+p(x)y=f(x), p(x), f(x)- - a<x<b 1 .
f(x)= 0, .
- y(n)+p1(x)y(n-1)++pn-1(x)y+pn(x)y=0
pi , y=ekx, k- . -
(kn+p1kn-1+.+pn-1 k+ pn) ekx=0
ekx . -
kn+p1kn-1+.+pn-1 k+ pn =0
- n- c k, y= ekx -.
1.k1, k2,,kn
: ek1x, ek2x,, eknx
2. k1= k2==km=k~,
k~- m - -, n- m
: e k~ x,x e k~ x,, xm-1 e k~ x, e km+1 x, e kn x
3. k1=α+iβ, k2= α-iβ, k3=γ+iδ, k4= γ-iδ,
: eαxcosβx, eαxsinβx, eγxcosδx, eγxsinδx, ek5x,, eknx
4. k1=α+iβ- m- - (m≤n/2), k2= α-iβ m-
: eαxcosβx, eαxsinβx, xeαxcosβx, xeαxsinβx,xm-1 eαxcosβx, xm-1 eαxsinβx,, ek2m+1x,, eknx
( ).
1. k1= k2==km=k~,
k~- m - -, n- m
: e k~ x,x e k~ x,, xm-1 e k~ x, e km+1 x, e kn x
2. k1=α+iβ- m- - (m≤n/2), k2= α-iβ m-
: eαxcosβx, eαxsinβx, xeαxcosβx, xeαxsinβx,xm-1 eαxcosβx, xm-1 eαxsinβx,, ek2m+1x,, eknx