GIA'I PHU.O.NG TRNH

5)

Gia'i phu.o.ng trnh:

^xy

⁰

^{=y(1 + lny−lnx)}

vo.i

^{y(1) =e}HD gia’i:

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

^y

⁰

^{= y}x(1 + lnyx)

, da.t

^y=zx

du.o..c:

^xz

⁰

^=zlnz• zlnz 6= 0⇒ dzzlnz = dxx ⇒lnz =Cx

hay

^lnyx =Cx⇔y=xe

^Cx

y(1) =e →C = 1.

V^a.y

^{y =xe}

^x