曲線在原點處的法平面方程為:()
A.x-y=0 B.y-z=0 C.x+y=0 D.x+z=0
A.x+y+z=0 B.x+y+z=1 C.x+y+z=2 D.x+y+z=3
曲面z=x2+y2在(-1,2,5)處的切平面方程是:()
A.2x+4y+z=11 B.-2x-4y+z=-1 C.2x-4y-z=-15 D.2x-4y+z=-5