= f (x) 0. = 0 f (x) 0, 0 , : 1) 0 , ; 2) 0 , .
. 0 , . . f '(x 0) = 0, f '(x) < 0 0 − δ < x < x 0, f '(x) > 0 0 < x < x 0 + δ (δ > 0). f (x) ( 0 − δ; 0) ( 0; 0 + δ), . . f (x 0) < f (x) Î ( 0, δ) = (0 − δ; 0 + δ), ≠ 0. , 0 .
, .
.
8.5. ( ).
= 0 0 = f (x) , , 0 , : 1) 0 , f ''(x 0) > 0; 2) 0 , f ''(x 0) < 0.
8.2. f (x) = .
. f '(x) = , , , .
f ''(x) = :
f ''() = 12 × 2 − 20 > 0, f ''(0) = −20 < 0, f ''() = 12 × 5 − 20 > 0.
, , , , min f (x) = f () = f () = 10, max f (x) = f (0) = 15.
.
8.8. = f (x) , ( 8.7). = f (x) , ( 8.8).
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8.6. ( ).
= f (x) , ; , .
8.3. f (x) = .
. f ''(x) = . f ''(x) < 0 < 2 f ''(x) > 0 > 2, (−¥; 2) (2; +¥).
8.9. = f (x) 0 ( 8.9), .
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