已知椭圆x^2/2+Y^2=1 过点A(2,1)椭圆的割线,求截得弦中点的轨迹方程

方法一（1）中点P(x,y)(yA-yB)/(xA-xB)=2xA+xB=2x,yA+yB=2yx^2/2+y^2=1x^2+2y^2=2(xA)^2+2(yA)^2=2.(1)(xB)^2+2(yB)^2=2.(2)(1)-(2):(xA+xB)*(xA-xB)+2(yA+yB)*(yA-yB)=0(xA+xB)+2(yA+yB)*(yA-yB)/(xA-xB)=02x+2*2y*...