GIA'I H^E. PHU.O.NG TRNH

194)

Gia'i h^e. phu.o.ng trnh:

dzdx =z−4y.HD gia’i:

Phu.o.ng trnh da.c tru.ng

^λ

²

^{−2λ+ 5 = 0.}

Khi do

^λ

1

= 1 + 2i,λ

2

= 1−2i.

H^e. thu^an nh^at co nghi^e.m

y=e

^x

(C

₁

cos 2x+C

₂

sin 2x), z= 2e

^x

(C

₂

cos 2x−C

₁

sin 2x).

Va nghi^e.m cu'a h^e. kh^ong thu^an nh^at

y=e

^x

(C

₁

cos 2x+C

₂

sin 2x), z= 2e

^x

(C

₂

cos 2x−C

₁

sin 2x)−e

^x

.dxdt =x+ 2y