有條maths數唔識!!!希望凌晨3點前有人幫我/3\\

the mid-point of AB = [(-4+2)/2 ,(3+6)/2]= (-1,4.5)
the slope of AB = (3-6)/(-4-2) = 1/2
the slope of required equation = -1/(1/2) = -2

the equation of the perpendicular bisector (中垂線)
by point slope form
(y-4.5 )/[x-(-1)]= -2
4x+2y -5 =0

2010-01-27 06:57:52 補充：
IF f ( 1 - 2x ) = 4x^2 +8x +2 , f(x)= ????
let y = 1-2x, then x = (1-2y)/2
f ( 1 - 2x ) = 4x^2 +8x +2
f(y)
=f[1- 2(1-2y)/2]
= 4[(1-2y)/2]^2 +8[(1-2y)/2] +2
= y^2 -6y +7
therefore f(y) =y^2 -6y +7
f(x) = x^2 -6x +7

check
f(x) = x^2 -6x +7
f ( 1 - 2x )=(1-2x)^2 -6(1-2x)+7
=...
= 4x^2 +8x +2