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
曲面z=y+lnx/z在點(diǎn)(1,1,1)處的法線方程是:()
A.(x-1)/1=(y-1)/1=(z-1)/-1 B.(x-1)/1=(y-1)/1=(z-1)/-2 C.(x-1)/1=(y-1)/-1=(z-1)/-2 D.x+y-z=1
在曲線x=t,y=t2,z=t3上某點(diǎn)的切線平行于平面x+2y+z=4,則該點(diǎn)的坐標(biāo)為:()
A.(-1/3,1/9,-1/27),(-1,1,-1) B.(-1/3,1/9,-1/27),(1,1,1) C.(1/3,1/9,1/27),(1,1,1) D.(1/3,1/9,1/27),(-1,1,-1)