M,N两点关于y轴对称,点M在y=1/2x上,点N在y=-x+3上,设M坐标为(a,b),则y=-abx方+(a-b)x的顶点坐标为?急用!

问题描述:

M,N两点关于y轴对称,点M在y=1/2x上,点N在y=-x+3上,设M坐标为(a,b),则y=-abx方+(a-b)x的顶点坐标为?
急用!

=[1\(x-3)-1\(x-2)]-[1\(x-3)-1\(x-1)]+[1\(x-2)-1\(x-1)]
=1\(x-3)-1\(x-2)-1\(x-3)+1\(x-1)+1\(x-2)-1\(x-1)
=0

b=1/2a
N是(-a,b)
则b=-a+3
所以a=2,b=1
则y=-2x^2+x=-2(x-1/4)^2+1/8
所以顶点(1/4,1/8)