求过两点M1（2，-1,5）和M2（-1,0,6）的直线方程(y+1.5)/(0.6+1.5)=(x-2)/(-1-2),(y+1.5)/2.1=(x-2)/(-3),-3(y+1.5)=2.1(x-2),-3y-4.5=2.1x-4.2,-3y=2.1x+0.3,y=-0.7x--0.1.
