(1)x²/16+y²/4=1
(2)弦端点A(x1,y1),B(x2,y2),x1²/16+y1²/4=1,x2²/16+y2²/4=1,相减
(x1+x2)(x1-x2)+4(y1+y2)(y1-y2)=0
中点x1+x2=4,y1+y2=-2,代入得
(y1-y2)/(x1-x2)=1/2
斜率1/2,…x-2y-4=0
(1)x²/16+y²/4=1
(2)弦端点A(x1,y1),B(x2,y2),x1²/16+y1²/4=1,x2²/16+y2²/4=1,相减
(x1+x2)(x1-x2)+4(y1+y2)(y1-y2)=0
中点x1+x2=4,y1+y2=-2,代入得
(y1-y2)/(x1-x2)=1/2
斜率1/2,…x-2y-4=0