已知复数z=3+4i，i为虚数单位，.z是z的共轭复数，则i.z=（）A.-45+35iB.-45-35iC.-425+325iD.-425-325i

Question

已知复数z=3+4i，i为虚数单位，

.

z

是z的共轭复数，则(i)/(.z)=（　　）

A. -

(4)/(5)+(3)/(5)i

B. -

(4)/(5)-(3)/(5)i

C. -

(4)/(25)+(3)/(25)i

D. -

(4)/(25)-(3)/(25)i

Answer 1

∵z=3+4i，
∴(i)/(.z)=(i)/(3-4i)=(i(3+4i))/((3-4i)(3+4i))=-(4)/(25)+(3)/(25)i．
故选：C．