问题
选择题
已知复数z满足z2+(2-i)2=0,则复数z为( )
A.2-i
B.±(1+2i)
C.-2±i
D.2±i
答案
∵复数z满足z2+(2-i)2=0,
设复数z=a+bi,(a,b∈R),
则有a2-b2+2abi=5-4i,
∴a2-b2=5,2ab=-4,
∴a=1,b=2,或a=-1,b=-2,
故复数z=1+2i或复数z=-1-2i,
故选:B.
已知复数z满足z2+(2-i)2=0,则复数z为( )
A.2-i
B.±(1+2i)
C.-2±i
D.2±i
∵复数z满足z2+(2-i)2=0,
设复数z=a+bi,(a,b∈R),
则有a2-b2+2abi=5-4i,
∴a2-b2=5,2ab=-4,
∴a=1,b=2,或a=-1,b=-2,
故复数z=1+2i或复数z=-1-2i,
故选:B.