设A={x x^2-x-12=0} B={x x^2-2ax+b=0},若B不等于空集,且A并B=A,求a,b的值_数学解答

设A={x x^2-x-12=0} B={x x^2-2ax+b=0},若B不等于空集,且A并B=A,求a,b的值

人气：354 ℃　时间：2019-09-29 03:25:44

解答

A:(x-4)(x+3)=0x=4,x=-3A={4,-3}B包含于A4a^2-4b>=0a^2-b>=0B｛4｝orB={-3}orB={4,-3}4a^2-4b=016-8a+b=0a^2=ba^2-8a+16=0a=4,b=162,B={-3}4a^2-4b=09+6a+b=0b=a^2(a+3)^2=0a=-3,b=93.B={4,-3}16-8a+b=09+6a+b=07-14...