, , u = f(x, y), , ..
j(, ) = 0, .
, .. .
u = f(x, y(x)).
:
=0 (1)
:
(2)
(2) l (1).
l , :
. . .
u = f(x, y) + lj(x, y) .
. f(x, y) = xy, :
2x + 3y 5 = 0
, .
.
, , .
: |
, , u = f(x, y), , .. j(, ) = 0, . , .. . u = f(x, y(x)). : =0 (1) : (2) (2) l (1).
l , : . . . u = f(x, y) + lj(x, y) . . f(x, y) = xy, : 2x + 3y 5 = 0 , . . , , .
: 2015-05-07; !; : 528 | : : : , . |