过点M(3,-1)且被电M平分的双曲线x²/4-y²=1的弦说在直线方程
问题描述：
过点M(3,-1)且被电M平分的双曲线x²/4-y²=1的弦说在直线方程
答
弦ABxA+xB=2xM=2*3=6yA+yB=2yM=2*(-1)=-2k(AB)=(yA-yB)/(xA-xB)=(y+1)/(x-3)[(xA)^2/4-(yA)^2]-[(xB)^2/4-(yB)^2]=1-1(xA+xB)*(xA-xB)-4*(yA+yB)*(yA-yB)=06-4*(-2)*(yA-yB)/(xA-xB)=03+4*(y+1)/(x-3)=03x+4y+13=0