在平面直角坐标系xoy上,给定抛物线L:y=
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x
2.实数p,q满足p
2-4q≥0,x
1,x
2是方程x
2-px+q=0的两根,记φ(p,q)=max{|x
1|,|x
2|}.
(1)过点,A(p
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131023214050376013822/SYS201310232140503760138020_ST/1.png)
p
2)(p
≠0),作L的切线交y轴于点B.证明:对线段AB上的任一点Q(p,q),有φ(p,q)=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131023214050376013822/SYS201310232140503760138020_ST/2.png)
;
(2)设M(a,b)是定点,其中a,b满足a
2-4b>0,a≠0.过M(a,b)作L的两条切线l
1,l
2,切点分别为E(p
1,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131023214050376013822/SYS201310232140503760138020_ST/3.png)
),E′(p
2,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131023214050376013822/SYS201310232140503760138020_ST/4.png)
p
22),l
1,l
2与y轴分别交于F,F′.线段EF上异于两端点的点集记为X.证明:M(a,b)∈X⇔|P
1|<|P
2|⇔φ(a,b)=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131023214050376013822/SYS201310232140503760138020_ST/5.png)
.
(3)设D={ (x,y)|y≤x-1,y≥
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(x+1)
2-
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131023214050376013822/SYS201310232140503760138020_ST/7.png)
}.当点(p,q)取遍D时,求φ(p,q)的最小值 (记为φ
min)和最大值(记为φ
max)
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