Question

A={x2-3x+2=o},B={x2-ax+(a-1)=0},c={x2-mx+2}.满足A∩B=B,A∪C=A,求a

Answer 1

A={x^2-3x+2=o}

A={x=2或者x=1}

B={x^2-ax+(a-1)=0}

x^2-ax+(a-1)=0

(x-a+1)(x-1)=0

B={x=a-1或者x=1}

因为A∩B=B,即B属于A

所以a-1=2或者a-1=1

a=3或者a=2

A∪C=A即C属于A

将x=2或者x=1代入x2-mx+2

得m=3