直线y=kx-2交曲线y^2-8x=0于A,B两点,若AB中点的横坐标是2,求线段AB的长

设AB中点D(x0,y0)由已知条件可知x0=2.y0=2k-2设A(x1,y1) B(x2,y2)代入抛物线y1^2-8x1=0y2^2-8x2=0两式相减得(y1^2-y2^2)-8(x1-x2)=0(y1+y2)(y1-y2)-8(x1-x2)=0两边同除以(x1-x2)2y0*k-8=02(2k-2)k-8=0得k=-1或者2当k...