= f (x), (). 0 Î (), δ . δ - 0 ( 0 − δ; 0 + δ) ( 0; δ).
8.4. δ- 0, (), Î ( 0; δ), ≠ 0 f (x 0) > f (x), 0 = f (x 0) = f (x) max f (x) ( 8.1).
Î ( 0; δ), ≠ 0 f (x 0) < f (x), 0 = f (x 0) = f (x) min f (x) ( 8.2).
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, ( ); ( 8.3).
8.5. . , , .
8.3. ( ).
.
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< 0 > 0;
> 0 < 0;
≤ 0,
≥ 0.
,
0 ≤ = f '(x 0) = ≤ 0,
f '(x 0) = 0. , 0 .
8.1. f '(x 0) = 0, , 0 . , f (x) = x 3, f '(x) = 3 x 2, f '(0) = 0, 0 = 0 , . . f (x) > 0 > 0 f (x) < 0 < 0 ( 8.4).
8.2. , . , = 0 = 1, ( 8.5).
= 0 = 0, . . ' = = 0 = 0 , ( 8.6).
8.6. , , . , , , .
, .
8.7. , = f (x) = 0, f (x 1) f (x 2) < 0 1, 2 , 1 < x 0 < x 2; , f (x 1) > 0, f (x 2) < 0; , f (x 1) < 0, f (x 2) > 0.
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