集合A{x/x2+x-2=0,x属于R},B={ax+3=0},若A交B＝B,求A取值范围

Question

集合A{x/x2+x-2=0,x属于R},B={ax+3=0},若A交B＝B,求A取值范围

Answer 1

A={x|x2+x-2=0,x∈R},B={ax+3=0},若A∩B＝B
A={x|x2+x-2=0,x∈R}
={ x| (x+2)(x-1)=0,x∈R}
= {-2,1}
if A∩B＝B => B is a subset of A
when x=-2
-2a+3=0
a = 3/2
when x=1
a+3=0
a=-3
ie a=-3 or 3/2 #