设集合A={2,4,a3_2a2-a+7},B={-4,a+3,a2-2a+2,a3+a2+3a+7}若A∩b+{2,5},求a_其他解答

设集合A={2,4,a3_2a2-a+7},B={-4,a+3,a2-2a+2,a3+a2+3a+7}若A∩b+{2,5},求a

人气：389 ℃　时间：2020-05-06 23:14:03

解答

A∩b={2,5},所以5属于A所以a³-2a²-a+7=5a³-2a²-a+2=0a²(a-2)-(a-2)=0(a+1)(a-1)(a-2)=0a=-1,1,2a=-1a+3=2a²-2a+2=5a³+a²+3a+7=4则AB都有4和A∩b={2,5}矛盾a=1a+3=4也是AB都...