P
{ξ > t + 2 | ξ > t}
ξ
f
ξ
(x) =
1
π
1
1+x
2
P
{ξ ≤ 1}
P
{|ξ| ≥ 1}
ξ
N(0, 1)
M
ξ cos ξ
M
ξ
1+ξ
2
ξ
f
ξ
(x) = a sin x x ∈
[0, π]
a
P
(|ξ| <
π
4
)
M
ξ
ξ
N(0, 1)
η =
ξ,
|ξ| ≤ 1,
−ξ,
|ξ| > 1.
η
M
η
D
η
ξ
λ > 0
M
ξ
2
,
M
ξ
1+ξ
N ξ
M
ξ
ξ η ξ ∈ N(0, 1)
η ∈ N(0, 4)
(ξ, η) 0 ≤ x ≤ 1, −4 ≤ y ≤ 0
ξ η ξ ∈ N(0, 4)
η ∈ N(0, 4)
(ξ, η) D = {(x, y) : 1 ≤ min(|x|, |y|), max(|x|, |y|) ≤ 2}
k n
1, 2, . . . , k
n
1
, . . . , n
k
(n
1
+ . . . + n
k
= n)