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问题: 看了就知道!~高二数学抛物线!

第二题

解答:

B. 3/2
y1=2*x2^2 ...(1) y2=2*x2^2 ...(2)
(y1+y2)/2 =(x1+x2)/2 +m ...(3)
(y1-y1)/(x1-x2) =-1 ...(4)
x1*x2 =-1/2 ...(5)
(1)-(2)==> y1-y2=2(x1-x2)(x1+x2) ==> x1+x2=-1/2 ...(6)
(5)(6)==> x1^2+x2^2=5/4
(1)+(2)==> y1+y2 =5/2
==> m =(y1+y2)/2 -(x1+x2)/2 =3/2 ==> B.