A(x1,y1)B(x2,y2)P(x,y)
x1+x2=2
y1+y2=2
3x1^2+4y1^2=12
3x2^2+4y2^2=12
两个式子相减,得
3(x1-x2)(x1+x2)+4(y1-y2)(y1+y2)=0
3(x1-x2)+4(y1-y2)=0
(y1-y2)/(x1-x2)=-3/4
k=-3/4
此弦所在的直线方程
y-1=-3(x-1)/4
4y-4=-3(x-1)
3(x-1)+4y-4=0
3x+4y-7=0