. :
= D(X) = M(
x M(X) .
1. .
2. ,
D(CX) = .
3.
D(X+Y) = D(X) + D(Y).
4.
D(X-Y) = D(X) + D(Y).
.
3. : ) -3, ) 4 + 3.
:
, .
1.
, . .
.
;
.
.
, , . .
- (,).
F() = P( <x).
:
1. 0 ≤ F() ≤ 1;
2. F() - ;
3. P(a ≤ x < ) = F(a) F();
4. , - , .
5. , ,
P(a ≤ x <b) = P(a < x ≤ b) = P(a ≤ x ≤ b) =P(a < x ≤ b).
6. (,d),
1. F() = 0 ≤ a;
2. F() =1 ≤ d;
3.
( ).
. f(x) ( )
.
:
1) f(x)≥ 0;
2) f(-∞)= f(-∞) = 0;
3) f(x) ;
4) F() =
5) P(;
6) .
,
.
1.
, :
1. 1?
2. 1?
3. ?
4. ?
.
:
|
|
f(x) =
(0 < < 3).
.
:
f(x) =
5
< < 3) =