集合A＝｛x\（－2）（x－a）＝0,a∈R｝B＝｛x\x²－5x＋6＝0｝求A∪BA∩B若A∩B＝A,求a的值

Question

集合A＝｛x\（－2）（x－a）＝0,a∈R｝B＝｛x\x²－5x＋6＝0｝求A∪B A∩B 若A∩B＝A,求a的值

Answer 1

A＝｛x|（x－2)（x－a)＝0,a∈R｝
= {2,a}
B＝｛x|x²－5x＋6＝0｝
= { x| (x-2((x-3)=0}
={2,3}
A∪B = {2,3,a}
A∩B = {2} if a ≠ 2 or a≠3
if A∩B＝A => A is subset of B
a=2 or a = 3