设z=f(x,y)在点(0,0)近旁有定义,则().
A.
B.曲面z=f(x,r)在点(0,0,z0)的法向量为(3,1,1)
C.曲线在点(0,0,z0)的切向量为(1,0,3)
D.曲线在点(0,0,z0)的切向量为(3,0,1)
设z=[sin(2π/3)+icos(2π/3)]2,i是虚数单位,则argz等于 ()
A.π/3
B.2π/3
D.4π/3
D.5π/3
设,证明:如果w(z)将实轴Imz=0映射为实轴Imw=0,则系数a,b,c,d一定可以取为实数.
设集合M={X∈R|X≤-1},集合N={∈R|Z≥-3},则集合MnN=()
A.{X∈R
B.一3≤X≤-1}
C.{Z∈R
D.Z≤-1}
E.{X∈R
F.X≥一3}
G.φ