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M={(x,y)|y=X³}其中x=-1,0,1,2,3,在集合M中任取三点能作三角形的概率为

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M={(x,y)|y=X³}其中x=-1,0,1,2,3,在集合M中任取三点能作三角形的概率为
M={(x,y)|y=X³}其中x=-1,0,1,2,3,在集合M中任取三点能作三角形的概率为
M={(x,y)| y=x³ }
M={(-1,-1),(0,0),(1,1),(2,8),(3,9) }
let A,B,C be points of triangle.
when A=(-1,-1),B= (0,0) => slope = 1
C can be (2,8) or (3,9) ( 2个选择)
when A=(-1,-1),B= (1,1) => slope = 1
C can be (2,8) or (3,9) ( 2个选择)
when A=(-1,-1),B= (2,8) => slope = 3
C can be(0,0),(1,1),(3,9) ( 3个选择)
when A=(-1,-1),B= (3,9) => slope = 5/2
C can be(0,0),(1,1),(2,8) ( 3个选择)
when A=(0,0),B=(1,1) => slope = 1
C can be (2,8),(3,9) ( 2个选择)
when A=(0,0),B=(2,8) => slope = 4
C can be(-1,-1),(1,1),(3,9) ( 3个选择)
when A=(0,0),B=(3,9) => slope = 3
C can be(-1,-1),(1,1),(2,8) ( 3个选择)
when A=(1,1),B=(2,8) => slope = 7
C can be(-1,-1),(0,0),(3,9) ( 3个选择)
when A=(1,1),B=(3,9) => slope = 4
C can be(-1,-1),(0,0),(2,8) ( 3个选择)
when a=(2,8),B=(3,9) => slope = 1
C can be (-1,-1),(0,0),(1,1) ( 3个选择)
total option =3 * 5C2 = 5.4/2 = 30
任取三点能作三角形的概率 = 27/30 = 9/10 #