y²=k²x²-2kx+1=4xk²x²-2(k+2)x+1=0x1+x2=2(k+2)/k²中点的横坐标=(x1+x2)/2=(k+2)/k²=1k²-k-2=0k=-1,k=2k=-1x²-2x+1=0x=1此时是相切不是两点k=24x²-8x+1=0x1+x2=2...