设弦与椭圆得交点坐标为(x1,y1),(x2,y2),
9/x1^2+4/y1^2=1
9/x2^2+4/y2^2=1
两式相减,因为A为中点,所以(x1+x2)/2=2,(y1+y2)/2=1
(y1-y2)/(x1-x2)=k,直线斜率求出了,因为过A,带入即可谢谢0 0