f(x) [ a,b ], (a,b), a b.
1 (: ). f(x) [ a,b ], .
g , ($c>0): (" x Î[ a,b ]½ f (x)½£c). (1)
, .. ("c>0) ($ x cÎ[ a,b ]): ½ f (x c)½>c. (2)
(2) c=1,2, , n, , ("nÎN) ($ x nÎ[ a,b ]): ½ f (x n)½>n. (3)
("nÎN) a £ xn £ b , {xn} . - : ${ }: =x. (4)
(3): ("kÎN) a £ £ b. (5)
(4) (5) xÎ[ a,b ]. f , (4) : . (6)
, (3) ("nÎN): , n=nk (k=1,2,), .. . : =+¥, k¥ n¥. (6), . (2) (1).n
2 (: ). f (x) [ a,b ], , ..:
($ x, h Î[ a,b ]): (f (x) = Ù f (h) = ). (7)
g 1 f (x) , E(f) : =M, =m. :
M= Û 1) , (8) . (9)
e = 1, , , , .., (9), { x n}: ("nÎN) (xnÎ[ a,b ] Ù f (x n) > M - ). (10)
(8), (10) : ("nÎN)(M - < f (x n) £ M). , n { f (xn)} , ..: . (11). { x n} : =xÎ[ a,b ]. f(x) x, : . (12)
, , (11), : M. =. , (12) : f (x) == . n
3 (-: ). f(x) [ a,b ] f(a)=A, f(b)=B, ("CÎ[A,B]) ($xÎ[ a,b ]): f(x)=C.
g, , - , , , .
f (a)=A<B=f(b) A<C<B. [ a,b ] 0 . :
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1) f (x 0)=C, .. x= 0 ;
2) f (x 0)¹C, , ( , ).
[ a 1 ,b 1] , . : x (f (x)=C); [ a n ,b n] , : f(an) < C <f(bn). (13)
x [ a n ,b n]: a n < x < b n Ù b n - a n = 0 n¥. f (x) = =x :
= = f (x). (14)
(13): ££ .
(14), , f(x)=C.n
4 (: ). f(x) [ a,b ] , [ a,b ] f (x).
f (x) D, .. :
. (15)
- , . , 1. , .
f (x) D, : ("e>0)($d>0):("x1ÎD)(" x2ÎD): . (16)
d e. (16) ( D). x 1, x 2Î D, d: , e.
(16) (15), - , D ( d , ).
(). , [ a;b ], .