, f(x) 䒺 [a,b].
s , .
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3, 1 2.
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1 1 3 , (1)
1 2 3 , (2)
( 3) , (3)
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1. . .
2. .
4. .
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1)
1. , .
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2)
. , , .
2. : 1) , 2) , , .
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Ҳ
, , < b
:
1. a > b,
2. a = b,
1
f(x) [a, b], [b, a],
2
f(x), g(x) [a, b], [f(x) g(x)] . (*)
, f(x) g(x) [a, b]. - ; - ξ [xi-1, xi] :
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f(x) g(x) ∃ , ∃ ( d ). , , [a, b]
г (*) (1), d 0.
3
f(x) [a, b], f(x) [a, b]. : .
fi(x) ( = 1, 2, , n) [a, b], ( [a, b].
4
f(x) [a, b], [a, c], [c, b], . ∀ a, b, c, : (1)
I) a < c < b. ᒺ [a, b] xi n [xi-1, xi]
S s = (2)
Wi - f(x) [xi-1, xi], Wi, Wi [a, c], [c, b].
f(x) [a, b], = 0
- 䒺 (2) , = 0, = 0, , f(x) [a, c] [c, b] .
:
(3)
, d → 0, (1)
II) - a, b, c, (1) . b < a < c. I
:
(1), .
:
f(x) - [a, b], [a, c], [c, b], .
5
:
1) f(x) [a, b];
2) ∀x [a, b]: f(x) ≥ 0
3) a < b
∀ [a, b] xi, ∀ [xi-1, xi], II ,
f(x) [a, b], :
∃
6
:
1) f(x) g(x) [a, b];
2) ∀x [a, b]: f(x) ≤ g(x);
3) a < b;
h(x) = g(x) f(x), , 0: h(x)≥0. 5, :
7
:
1) f(x) [a, b];
2) ∀x [a, b]: m ≤ f(x) ≤ M;
3) a < b;
:
m(b a) ≤ M(b a)
6, y=m, y = f(x) y = f(x), y = M.
8
:
1) f(x) [a, b];
2) a < b
|f(x)| [a, b] : | (1)
ᒺ [a, b] xi n [xi-1, xi]. .
||α| - |β|| ≤ | α β|(∀α, β R) (2)
∀ , : ||f()| - |f()|| ≤ |f()| f()| => ||f()| - |f()|| ≤ |f()| f()|
≤ (3), , f(x), |f(x)| . (3) :
(4)
f(x) [a, b],
(4) => , |f(x)| - [a, b]. (1) . |f(x)| ≤ f(x) ≤ |f(x)| (6), (7) |
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9.
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1. ;
2. .
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2) 7. :
9 , :
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