高中数学选修1-2
3.2.2 复数代数形式的乘除法运算
1.(1-2??)(3+4??)(-2+??)等于 ( ). A.20+15i C.-20-15i
B.20-15i D.-20+15i
2.(1+i)20-(1-i)20的值是 ( ).
A.-1 024 B.1 024 C.0 D.512
3.
(?1+√3??)3
?2+??
(1+??)6
+1+2??的值是 ( ).A.0 B.1 C.i D.2i
4.复数z满足(1+2i)z?=4+3i,那么z= ( A.2+i B.2-i C.1+2i D.1-2i
5.若x=1?√3??,那么
12
??2???
= ( A.-2 B.-1 C.1+√3??
D.1
6.设复数z=1+√2i,则z2-2z=________.
7.若z??1=a+2i,z2=3-4i,且1
??2为纯虚数,则实数a的值为________.
8.设f(z+i)=1-z?,z1=1+i,z2=1-i,则f(11
??1
+??2
)=________.
9.计算(1) (1+??)6
+√2+√3??1???
√3?√2??;
(2).(16
2+√32??)
10.复数z=(1+??)2+3(1???)
,若z2+??
2+??
??<0,求纯虚数a.
1
).
).
高中数学选修1-2
11复数z=
(1+??)3(??+????)
1???
且|z|=4,z对应的点在第一象限,若复数0,z,对应的点是正三角
形的三个顶点,求实数a、b的值.
2
高中数学选修1-2
[答案]
1.[解析] (1-2??)(3+4??)(-2+??)=(3+4??-6??+8)(-2+??)=(11-2??)(-2+??)
=-22+11??+4??+2=-20+15??.
[答案] D
2.[解析] (1+i)20-(1-i)20=[(1+i)2]10-[(1-i)2]10= (2i)10-(-2i)10=(2i)10-(2i)10=0. [答案] C 3.[解析] 原式=[答案] D
4.[解析] ???=1+2??=(1+2??)(1?2??)== (10-5i)=2-i, ∴z=2+i. [答案] A
5.[解析] ∵x2-x=x(x-1)=1?√3??(1?√3???1).=·1?√3???1?√3??=- (1-√3i)(1+√3i)
2
2
2
2
4+3??
(4+3??)(1?2??)(1+√3??)[(1+??)]
3
+(1+2??)??=23
(?2+??)??
+=-+i=2i,
=-1,
所以??2???=-1,故选B. [答案] B
6.[解析] ∵z=1+√2i
∴z2-2z=z(z-2)=(1+√2i)(1+√2i-2) =(1+√2i)(-1+√2i)=-3. [答案] -3 7.[解析]
=3?4??=
??+2??
(??+2??)(3+4??)
25
1
=
(3???8)+(4??+6)??
25
3???8=0
∴{∴a=. 4??+6≠0[答案]
8.[解析] 令z+i=t,得z=t-i, ???f(t)=1-(????????)=1-i-??, +=1+??+1???=(1+??)(1???)=1. ∴ f(??+??)=f(1)=1-i-1=-i.
1
2
112
11
[答案] -i
3
高中数学选修1-2 9.[解析] (1)原式=i6+((√2+√3??)??√3?√2??)??=-1+i.
22
(2)法一 原式=[(1
√3212
+
2
??)]=(?2+
√32
??) =?1
2?√32i
法二 ∵(?1?√33
22
??)=1, ∴原式==(?1?√3??)3(?1?√32222
??) =?1
?√32
2??
10.[解析]由z2+<0可知z2+是实数且为负数.z=
(1+??)2+3(1???)
3???
2+??
==2+??=1-i.
∵a为纯虚数,∴设a=mi(m≠0),则 z2+??
????
?????????=(1-i)2+
1???
=-2i+2
=-??
??
2+(2?2)i<0, ∴{???
??
2<02
?2=0
∴m=4,∴a=4i.
11.[解析] z=2i·i(a+bi)=-2a-2bi. 由|z|=4,得a2+b2=4,
∵复数0,z,???对应的点构成正三角形, ∴|??????|=|??|
把z=-2a-2bi代入化简得|b|=1.
又∵z对应的点在第一象限, ∴a<0,b<0. 由①②得{??=?√3??=?1
故所求值为a=-√3,b=-1. 4
①②
高中数学选修1-2课时作业4:3.2.2 复数代数形式的乘除运算
![](/skin/haowen/images/icon_star.png)
![](/skin/haowen/images/icon_star.png)
![](/skin/haowen/images/icon_star.png)
![](/skin/haowen/images/icon_star.png)