P(x1,y1)Q(x2,y2)x1^2/16+y1^2/4=1x2^2/16+y2^2/4=1y1/x1*y2/x2=-1/4y2=-0.25x1x2/y1(x2^2-x1^2)/16+(y2-y1)(y2+y1)/4=0(x2^2-x1^2)/16+(-0.25x1x2+x1^2/4-4)(-0.25x1x2+4-x1^2/4)/(16-x1^2)=0(x2^2...