4、选2
5、选2
1. (1) (3/10)*(2/9)=1/15
(2) (7/10)*(3/9)=7/30
(3) 1/15+7/30=3/10
2. (1) f(y)=0 (y0)
(2) f(y)=0 (y=0)
先做这么些吧,有空再帮你算
4、选2
5、选2
1. (1) (3/10)*(2/9)=1/15
(2) (7/10)*(3/9)=7/30
(3) 1/15+7/30=3/10
2. (1) f(y)=0 (y0)
(2) f(y)=0 (y=0)
先做这么些吧,有空再帮你算