已知复数z=(a-1)+(a+1)i(a∈R,i为虚数单位)是纯虚数,则a=( ) A.-1 B.1 C.±1 D.0
问题描述:
已知复数z=(a-1)+(a+1)i(a∈R,i为虚数单位)是纯虚数,则a=( )
A. -1
B. 1
C. ±1
D. 0
答
∵复数z=(a-1)+(a+1)i(a∈R,i为虚数单位)是纯虚数,
∴
,
a−1=0 a+1≠0
∴a=1.
故选B.