已知z∈C,若|z|-.z=2-4i,则4+3iz的值是( ) A.1 B.-1 C.i D.-i
问题描述:
已知z∈C,若|z|-
=2-4i,则. z
的值是( )4+3i z
A. 1
B. -1
C. i
D. -i
答
设z=a+bi,|z|-
=2-4i,. z
则a=3,b=-4,
∴z=3-4i.
=4+3i z
=4+3i 3−4i
(4+3i)(3+4i) 25
=
=i.i(4+3i)(4−3i) 25
故选C.