当AB垂直于x轴时,方程为x=p/2,代入y^2=2px可得y^2=p^2,得y1=-p,y2=p,x1=x2=p/2,计算可得.当AB不垂直与x轴时,设方程为y=k(x-p/2),由y^2=2px得x=y^2/2p代入直线方程化简得ky^2-2py-kp^2=0,所以y1y2=(kp^2)/k=-p^2x1x2=... 当AB垂直于x轴时,方程为x=p/2,代入y^2=2px可得y^2=p^2,得y1=-p,y2=p,x1=x2=p/2,计算可得.当AB不垂直与x轴时,设方程为y=k(x-p/2),由y^2=2px得x=y^2/2p代入直线方程化简得ky^2-2py-kp^2=0,所以y1y2=(kp^2)/k=-p^2x1x2=...