根据空间直线的两点式：(x-x1)/(x2-x1) = (y-y1)/(y2-y1) = (z-z1)/(z2-z1) ,
可得所求直线方程为：(x+2)/2 = (y-1)/(-2) = (z-3)/(-1) ,
即：(x+2)/2 = (1-y)/2 = 3-z .