[a, b] (a, b), c, (a, b), : f(b) - f(a) = f′(c)(b - a). (1)
. 4.1.
. . f(x) A(a;f(a)) B(b;f(b)). AB. L, AB, , f(x) (a, b). L AB, L f(x) , L f (x) c (a, b). M, MN f(x), AB. , MN AB ( ) . MN f′(c), AB (f(b) -∙ f(b))/(b-a), :
(1). , , (a, b), f(x) MN. f(x), , (1) .
. f′(x) > 0 (a; b), (a; b) f (x). f′(x) < 0 (a;b), (a;b) f(x) .
. t 1 t 2 (a; b), t 2> t 1. c (t 1; t 2), f (t 2) f (t 1) = f′ (c)(t 2 t 1). f′ (x) > 0 x (a; b), f′ (c) > 0, t 2 > t 1, f (t 2) f (t 1) > 0. , f (x) (a; b) . .
x 0 f (x), , x :
f (x) > f (x 0).
x 0 f (x), , x : f (x) < f (x 0).
. 4.2.
. 4.3.
.
: f (x) , .
|
|
, , .
f′ (x 0) = 0, , x 0 . y = x 3. x =0 , . 4.4.
. 4.4.
, , .
, , , .
, , , , . , , , .
f (x) x 0. :
1) f′ (x) < 0 (a; x 0) f′ (x) > 0 (x 0; b), x 0 f (x);
2) f′ (x) > 0 (a; x 0) f′ (x) < 0 (x 0; b), x 0 f (x);
.
f′ (x) < 0 (a; x 0) f (x) x 0, f (x) (a; x 0], x ∈(a; x 0) f (x)> f (x 0).
f′ (x) > 0 (x 0; b) f (x) x 0, f (x) (x 0; b ], x ∈(x 0; b) f (x)> f (x 0).
, x ≠ x 0 (a; b) f (x)> f (x 0), x 0 f (x).
.