Question

1.设A=｛2,-1.x²-x+1｝B=｛2y,-4,x+4｝C=｛-1,7｝且 A∩B=C 求x y的值

Answer 1

1.设A=｛2,-1,x²-x+1｝B=｛2y,-4,x+4｝C=｛-1,7｝且 A∩B=C 求x y的值

A=｛2,-1,7}

B={-4,-1,7}

得x²-x+1=7

所以x=3,x+4=7

2y=-1

y=-1/2

2.设A=｛a²,a+1,-3｝ B=｛a-3,2a-1,a²+1｝ A∩B=｛-3｝求a的值

a²+1>a²

a²+1>-3

所以有a²+1≠a+1

得a≠0

a-3≠-3

必有2a-1=-3

得a=-1