(X, Y )
(0, 0) (5, 0) (5, 2) (0, 2)
(X, Y )
P(X + Y e" 3)
(X, Y )
EX3Y
X Y
X Y
1/2 X + Y
X + Y - 1
(X, Y )
(0, 0) (2, 0) (0, 2) X + Y
X/Y
(X, Y )
2
g(x, y) = (x2 + y2)1{(x,y):x2 .
+y2d"1}
Ä„
X
EY
"
X + Y 2X
2
X2 + Y
X
X1 X2 . . . Xn
[0, 1] Y =
max(X1, X2, . . . , Xn)
X Y X
0 1 Y
0 2
X + 2Y
2X + Y X + 3Y
XY
 (X, Y )
(1, 0) (0, 1) (-1, 0) (0, -1)
X
X Y
X + Y X - Y

1/3 0
3/5 311 U((0, 5))
4
0 25/12
U((0, 2))
"
4 2
gX(x) = 1 - x2(1 + x2)1(-1,1)(x) 0 gX2 2(x) =
+Y
Ä„ 3 3
2x1[0,1](x)
gY (t) = ntn-11[0,1](t).
9 8
X 0
Ã2 EX4 = 3Ã4
gX(t) = (1 - |t|)1(-1,1)(t) Á(X, Y ) = 0