解答：(x+x')/2-(y+y')/2-2=0(y-y')/(x-x')=-1这个是方程组x-y+x'-y'-4=0 ①x+y-x'-y'=0 ②①-② -2y+2x'-4=0∴ x'=y+2然后，得到y'=x-2
