设它的直线方程是y=kx (k≠0)4x+y+6=0,y=kx 4x+kx+6=0,x=-6/(4+k)∴直线和4x+y+6=0的交点是(-6/(4+k),kx)3x-y-1=0,y=kx 3x-kx-1=0,x=1/(3-k)∴直线和3x-kx-1=0的交点是(1/(3-k),kx)∵截得的线段的中点恰好是坐标原点...