1: ( ( (1815-1897)- )). , , , .. [a, b] M £ f(x) £ M.
, , 0, , [a, b] , 0, 0.
2: , [a, b], .
.. 1 2, f(x1) = m, f(x2) = M,
m £ f(x) £ M
( f(x) = sinx).
.
3: ( ). , [a, b], .
4: f(x) = 0, 0, .
5: ( (1781-1848) ). f(x)- [a, b] , , f(x) = 0.
.. sign(f(a)) ¹ sign(f(b)), $ 0: f(x0) = 0.
. y=f(x) x0, .
,
. ,
,
α , .. , Δ x →0.
Δ y = f '(x 0) Δ x +αΔ x => Δ y →0 Δ x →0, . f(x) f(x 0 ) →0 x → x 0, , f(x) x 0. .
. f 0 ,
Δ, .
f 0 f`(0)
, x0, . D1 - , f . x∈D1 f`(x), D1. y=f(x) f` y`.
f