经过点P (2,-3)作圆x^2,y^2=20的弦AB,且使得P平分AB,则弦AB所在的直线的方程是

A(x1,y1),B(x2,y2),P(2,-3)P是AB中点:1)x1+x2 = 2*2即x1+x2=42)y1+y2 = 2*(-3)即y1+y2=-6A,B在圆上:3)x1^2+y1^2 = 204)x2^2+y2^2 = 203) - 4)(x1-x2)*4 =(y2-y1) * (-6)化简,(y1-y2)/(x1-x2) = 4/6 = 2/3这就是斜率2...