A={2x2-ax+b=0},B={bx2+（a+2）x+5+b=0},且A交B={2分之1},求A并B?急求,最迟今天晚上!还有一道英语题：短文改错 1.This is my first week in senior middle school.Now Iam 2.study in a new school and none my old friends3.have come to
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A={2x2-ax+b=0},B={bx2+（a+2）x+5+b=0},且A交B={2分之1},求A并B?急求,最迟今天晚上!还有一道英语题：短文改错 1.This is my first week in senior middle school.Now Iam 2.study in a new school and none my old friends3.have come to
A={2x2-ax+b=0},B={bx2+（a+2）x+5+b=0},且A交B={2分之1},求A并B?
急求,最迟今天晚上!
还有一道英语题：短文改错
1.This is my first week in senior middle school.Now Iam
2.study in a new school and none my old friends
3.have come to this school with me.I felt very lonely by the begginning.
4.But two days ago,I made friend with one of my new
5.classmates.His home was very close to the school,so he
6.can go home every day.He invited me have supper in
7.his home on yesterday.His mothor is a very kind-hearted
8.woman.She said that it was very importantly to have some
9.good friends in senior middle school.I am sure I will
A={2x2-ax+b=0},B={bx2+（a+2）x+5+b=0},且A交B={2分之1},求A并B?急求,最迟今天晚上!还有一道英语题：短文改错 1.This is my first week in senior middle school.Now Iam 2.study in a new school and none my old friends3.have come to
因为A交B=1/2,所以1/2是两个方程的公共根
代入方程得：1/2-1/2a+b=0,1-a+2b=0
1/2a+5/4b+6=0,2a+5b+24=0
所以a=-43/9 b=-26/9
所以集合A是18x^2+43x-26=0,集合B是-26x^2-25x+19=0,
用韦达定理,集合A中：x1+1/2=-43/18,1/2x1=-13/9
所以集合A是x1=-26/9,x2=1/2
同理：集合B是x1=-19/13,x2=1/2
所以A并B={x|x=1/2,-26/9,-19/13}