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复数(5+5i)3(3-4i)4+3i=()A.-105i-105B.105+105iC.105-105iD.-105

题目详情
复数
(
5
+
5
i) 3 (3-4i)
4+3i
=(  )
A. -10
5
i-10
5
B. 10
5
+10
5
i
C. 10
5
-10
5
i
D. -10
5
+10
5
i
▼优质解答
答案和解析
(
5
+
5
i) 3 (3-4i)
4+3i
=
10i(
5
+
5
i)(3-4i)
4+3i

=
10
5
+70
5
i
4+3i
=
(10
5
+70
5
i)(4-3i)
25

=
250
5
+250
5
i
25
=10
5
+10
5
 i,
故选 B.