题目内容
已知z1=2+i,z2=1-2i,则复数z=
-2i的模等于( )
i+
| ||
| z1-1 |
A.
| B.2
| C.
| D.
|
∵z1=2+i,z2=1-2i,
∴z=
-2i
=
-2i
=
-2i
=
-2i
=2+i-2i
=2-i,
∴复数z=
-2i的模=
.
故选D.
∴z=
i+
| ||
| z1-1 |
=
| i+1+2i |
| 2+i-1 |
=
| 1+3i |
| 1+i |
=
| (1+3i)(1-i) |
| 2 |
=2+i-2i
=2-i,
∴复数z=
i+
| ||
| z1-1 |
| 5 |
故选D.
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