ha8000
幼苗
共回答了17个问题采纳率:88.2% 举报
(1)∵除了负数就是正数就这两种情况,∴P(正数)=
3
6=
1
2;
(2)根据题意,画表格或画树状图或列举法说明均可,
甲
乙 1 2 3 -1 -2 -3
1 (1,1) (2,1) (3,1) (-1,1) (-2,1) (-3,1)
2 (1,2) (2,2) (3,2) (-1,2) (-2,2) (-3,2)
3 (1,3) (2,3) (3,3) (-1,3) (-2,3) (-3,3)
-1 (1,-1) (2,-1) (3,-1) (-1,-1) (-2,-1) (-3,-1)
-2 (1,-2) (2,-2) (3,-2) (-1,-2) (-2,-2) (-3,-2)
-3 (1,-3) (2,-3) (3,-3) (-1,-3) (-2,-3) (-3,-3)由上图可知,点(x,y)的坐标共有36种等可能的结果,
其中点(x,y)落在第一象限的共有9种,
所以,P(点(x,y)落在第一象限)=
9
36=
1
4.
1年前
7