1)A={2,3,4,6,8,12,24}
B={2,3,6,9,18,27,54}
A∩B={2,3,6}
2)a-1=3或 a²-3a-1=3
a=4 a=-1或a=4
当a=4时B={ 5,7,18}不全题意
所以实数a=-1