1.1.2 . . , , z =f(x, ) .
zx z , z . z z , z y .
:
(1.1.2)
1.1.2. z= xy (2;3).
(1.1.2)
zx (, ) = x (ln z)' x = x (y ln x)' x= ,
Ezy (x, y) = y (ln z)' y = y (y ln x)' y = ln .
, zx (2,3) =3, zy (2;3) = 3ln 2.
(1.1.2) , 1 3 1.1.2. . , . .
4 '. z = f (x, ), = j (t) = y (t) z no t t 0
zt = zxxt + zyyt, (1.1.3)
zx, zy z (j (t 0), y (t 0)), xt, yt t t 0.
1= f 1( 1, 2 ), y 2 =f 2 (x 1, x 2 ) 4 , 22:
, , .
5'. 1= g 1(y 1, y 2), x 2= g 2(y 1, y 2) 1= f 1( 1, 2 ), y 2 =f 2 (x 1, x 2 ). xy yx.
. . i i - , i (i = 1,2). (, ) (, ) , 1 2:
1= D 1(p 1, p 2), x 2= D 2(p 1, p 2) (1.1.4)
, , , , . , , (1.2.4) 1 2 :
p 1= p 1( 1, 2), p 2 =p 2 (x 1, x 2). (1.1.5)
(1.1.4) (1.1.5) . 5' .
1.1.3. 1=10 p 1-1.2 p 20.8, x 2=12 p 1-0.9 p 2-0.7. (x 1 , x 2 ).
, , , 1% 0.8%. , x -1.
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