若x是纯虚数,y是实数,且2x-1+i=y-(3-y)i,则x+y等于(  ) A.1+52i B.-1+52i C.1-52i D.-1-52i

问题描述:

若x是纯虚数,y是实数,且2x-1+i=y-(3-y)i,则x+y等于(  )
A. 1+

5
2
i
B. -1+
5
2
i
C. 1-
5
2
i
D. -1-
5
2
i

∵x是纯虚数,设x=ai(a≠0),
又y是实数,且2x-1+i=y-(3-y)i,
∴(2a+1)i-1=y-(3-y)i,

y=−1
2a+1=y−3
,解得a=-
5
2
,y=-1,
∴x+y=-
5
2
i-1,
故选:D.