TM NGHI^E.M RI^ENG CU'A PHU.O.NG TRNH

74)

Tm nghi^e.m ri^eng cu'a phu.o.ng trnh:

^x

²

^y

⁰

^=y(x+y)

thoa' ma~n di^eu ki^e.n d^au

^{y(−2) =−4}

.

HD gia’i:

Do

^{y(−2) =−4}

n^en

^y6≡0

. D - u.a phu.o.ng trnh v^e phu.o.ng trnh Bernouilli:

y

⁰

−1y= y

²

x

²

. Ti^ep tu.c da.t

^{z =y}

⁻¹

du.a phu.o.ng trnh v^e PT tuy^en tnh

^z

⁰

^{+ 1}xz =− 1x

²

.

NTQ cu'a phu.o.ng trnh thu^an nh^at tu.o.ng u.ng:

^{z = Cx}

, bi^en thi^en hang s^o du.o..c

C(x) = Cx− 12x

. Nhu. v^a.y nghi^e.m cu'a phu.o.ng trnh ban d^au la:

^y= _Cx^2x

2

−1

. D - i^eu ki^e.n

d^au cho

^{C = 1}