1.復(fù)數(shù)(i為虛數(shù)單位)的共軛復(fù)數(shù)是( )
A.1+i B.1-i
C.-1+i D.-1-i
[解析] ==1+i,
∴的共軛復(fù)數(shù)為1-i,故選B.
[答案] B
2.已知復(fù)數(shù)z1=(1+i)(i為虛數(shù)單位),復(fù)數(shù)z2的虛部為2,且z1·z2是實(shí)數(shù),則z2=________.
[解析] z1=(1+i)=2-i.
設(shè)z2=a+2i,a∈R,
則z1·z2=(2-i)·(a+2i)=(2a+2)+(4-a)i,
因?yàn)?i>z1·z2∈R,所以a=4.所以z2=4+2i.
[答案] 4+2i
3.若復(fù)數(shù)z滿足i·z=1+2i,其中i是虛數(shù)單位,則z的實(shí)部為_(kāi)_______.
[解析] ∵i·z=1+2i,∴z==2-i,故z的實(shí)部為2.
[答案] 2