x -direction =iy -direction =jz -direction =k(2,-1,5)x(0,-1,3)=(2i-j+5k)x(-j+3k)=(-2k-6j)+(-3i) +(5i)=2i-6j-2k求过点(1,-1,3)且平行于向量(2,-1,5)和(0,-1,3)的平面方程2(x-1)-6(y+1)-2(y-3) =0
