集合A={-4,x+3,x2-2x+2,x3+x2+3x+7}B={2,4,x3-2x2-x+7},A交B={2,5},求x的值_数学解答

集合A={-4,x+3,x2-2x+2,x3+x2+3x+7}
B={2,4,x3-2x2-x+7},A交B={2,5},求x的值

人气：300 ℃　时间：2020-05-23 20:54:44

解答

A交B={2,5},则B中有x³-2x²-x+7=5x³-2x²-x+2=0x²(x-2)-(x-2)=0(x+1)(x-1)(x-2)=0x=1,x=-1,x=2代入Ax=1,A={-4,4,1,12},没有2和5x=-1,A={-4,2,5,4},这样A交B={2,5,4},不成立x=2,A={-4,5,2,25}...