3.1. f (x, y) - n,
f (tx, ty) º t n f (x, y),
t .
n = 0
-
,
f (tx, ty) =
f (x, y).
,
f (x, y) = x 2 - xy
,
f (tx, ty) = (tx)2 - (tx) × (ty) = t 2 (x 2 - xy) = t 2 × f (x, y),
f (x, y) = 4 x - 9 y
x + 7 y
-
,
f (tx, ty) = 4( tx )-9( ty ) = t (4 x -9 y) = 4 x -9 y =
f (x, y).
tx + 7(ty)
t (x + 7 y)
x + 7 y
3.2.
¢ =
f (, y)
,
f (, y)
-
. -
P (, ) dx + Q (, y) dy = 0,
,
(, )
Q (, )
.
3.3. () u () - :
u = y x
y = u × x.
.
3.4. , -
æ y ö
, . .
f (x, y) = jç
è
÷, -
x ø
.