y = f (x) 0. f 0
. (4.1)
, , , . (4.1)
= + , (4.2)
, .
(4.2)
. (4.3)
(4.3) .
y = f (x) 0, f 0 df ( 0).
,
df ( 0)= . (4.4)
(4.3) :
. (4.5)
f (x)= x, . , . , (4.4)
df ( 0)= . (4.6)
(4.5) , .
, . (4.7)
(4.7) , 0.
(4.7) ,
. (4.8)
, ,
. (4.9)