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1.3复数(精讲)(基础版)思维导图考点一复数的实部、虚部【例1】(2022·湖北武汉·二模)已知复数11iz=+,则z的虚部为()A.1−B.1C.12−D.12【答案】C【解析】因为()()11i11i1i1i1i22z−===−++−,所以z的虚部为12−.故选:C.【一隅三
反】1.(2022·辽宁·建平县实验中学模拟预测)已知复数3i1iz+=+,则复数z的虚部为()A.1−B.1C.i−D.i【答案】A【解析】()()()()3i1i3i42i2i1i1i1i2z+−+−===
=−++−,其虚部为1−.故选:A.2.(2022·安徽黄山·二模)已知复数z满足(1i)32i+=+z,则z的虚部为()A.12B.1i2−C.12−D.1i2【答案】A考点呈现例题剖析【解析】(1i)32iz+=+,()()()()3+2i1i3+2i5i51i1i1i1i222z−−==
==−++−,5122iz=+,故复数z的虚部为12.故选:A考点二复数的几何意义【例2-1】(2022·天津市宁河区芦台第一中学模拟预测)已知复数z满足()12i43iz+=−(其中i为虚数单位),则复数z对应点的坐标为_____.【答案】()1,2−
【解析】2255(12i)5(12i)|43i|4(3)5,12i12i(12i)(12i)5z−−−=+−=====−++−即复数z对应点的坐标为()1,2−故答案为:()1,2−【例2-2】(2022·河南)若复数z满足()2i2i3z−=+(i为虚
数单位),则z在复平面内对应的点位于()A.第一象限B.第二象限C.第三象限D.第四象限【答案】D【解析】由()2i2i3z−=+,所以()()()()2i32i2i347i2i2i2i55z+++===+−−+,所以47i55z=−,
在复平面内对应的点是47,55−,位于第四象限,故选:D.【一隅三反】1.(2022·北京·模拟预测)在复平面内,复数23iz=−−,则z对应的点位于()A.第一象限B.第二象限C.第三象限D.第四象限【答案】B【解析】由2
3iz=−−,可得23iz=−+,在复平面内,复数z对应的点为()2,3−,位于第二象限故选:B2(2022·山西临汾)在复平面内,复数z对应点的坐标为()1,1−,则1iz+=()A.iB.-iC.1+iD.1-i【答案】A【解析】因为复数z对应点的
坐标为()1,1−,所以1iz=−,所以()()()21i1i1i2ii1i1i1i2z+++====−−+.故选:A.3.(2022·江西·二模)()()2i45i−+在复平面内对应的点位于()A.第一象限B.第二象
限C.第三象限D.第四象限【答案】A【解析】()()2i45i810i4i5136i−+=+−+=+,故()()2i45i−+在复平面内对应的点为()13,6,位于第一象限.故选:A.考点三数的分类【例3-1】(2022·辽宁·二模)设1iz=+(i为
虚数单位),若()Razaz+为实数,则a的值为()A.2B.2−C.1D.1−【答案】A【解析】i1i1i(1)(1)i1i222aaaaaazz−+=++=++=++−+,因为()Razaz+为实数,所以102a−=,解得2a=.故选:A.【例3-2】(2022·安徽省)已
知复数1i1iaz+=+为纯虚数(其中i为虚数单位),则实数a=()A.1B.-1C.2D.-2【答案】B【解析】()()()()1i1i1i11i1i1i1i22aaaaz+−++−===+++−,由题意得:102a+=,解得:1a=−故选:B【一隅三反】1.(2022·广东广州·二模)
若复数i1imz−=+是实数,则实数m=()A.1−B.0C.1D.2【答案】A【解析】依题意,(i)(1i)1(1)i11i(1i)(1i)222mmmmmz−−−−+−+===−+−,因Rm,且z是实数,则1=02m+,解得1m=−,所以实数
1m=−.故选:A2.(2022·河南·模拟预测(理))若2izmm=++为纯虚数,其中Rm,则4iz−=()A.12i2−−B.12i2−+C.12i2+D.12i2−【答案】C【解析】依题意,200mm+=
,解得2m=−,故224i4i4ii12i2i2i2z−−−===+−−.故选:C3.(2022·甘肃兰州·一模(理))设i为虚数单位,若复数()()1i1ia++是纯虚数,则实数=a()A.-1B.0C.1D.2【答案】C【解析】复数()()()(
)1i1i11iaaa++=−++,因为复数()()1i1ia++是纯虚数,所以1010aa−=+,解得1a=,故选:C考点四复数的模长【例4】(2022·浙江·模拟预测)若1iz=−(i为虚数单位),
则22zz+=()A.2B.22C.4D.25【答案】D【解析】()()2221i21i24izz+=−+−=−224+16=25zz+=故选:D.【一隅三反】1.(2022·安徽·模拟预测(文))设33i1iz+=+(i
为虚数单位),则z=()A.2B.3C.5D.13【答案】C【解析】由()()()()33i1i3i3i33ii112i1i1i1i1i2zz++++++−=====++−−+,所以22125z=+=,故选:C2.(2022·江西萍乡·二模(文))已知复数z满足3
2i(1i)z=+(i为虚数单位),则z=()A.2B.22C.1D.12【答案】D【解析】因为32ii1(1i)2i2z==−=−+,所以12z=,故选:D3.(2022·山西·二模(理))22ii3i−=+()A.515i22+B.515i22−C.13i22+D.13i2
2−【答案】C【解析】()()()()22ii5i3i513i13i3i3i3i1022−−+===+++−.故选:C.4.(2022·河南·二模(理))设复数12i2iz+=−(i是虚数单位),则zzz+的值为()A.22B.2C.2D.3【答案】B【解析】()()()
()12i2i12ii2i2i2iz+++===−−+,故()()iii1i2zzz+=−+−=−=.故选:B.5.(2022·江苏·海安高级中学二模)已知i为虚数单位,复数z满足|i||3i|zz−=+,则z的虚部为()A.2B.1C.-2D.-1【答案】A【解析】令()i,za
babR=+,则izab=−,22|i||ii|(1)zabab−=+−=+−,22|3i||(3)i|(3)zabab+=+−=+−,∴|i||3i|zz−=+,2222(1)(3)abab+−=+−,∴2b=,故选:
A.考点五复数的计算【例5-1】(2022·福建龙岩·模拟预测)复数z满足()31i22iz−=−+,则z=()A.2B.2−C.2iD.2i−【答案】D【解析】()31i22iz−=−+,()()()()322i1i22i22i2i1i1i1i1iz−−
+−+−−====−−−−+.故选:D.【例5-2】(2022·江苏·新沂市第一中学模拟预测)复数20221i1i−=+()A.iB.i−C.1D.1−【答案】D【解析】因为()()()21i1ii1i1i1
i−−==−++−,所以()()20222022202220224505221ii1iii11i+−=−=−===−+故选:D【一隅三反】1.(2022·山西省运城中学校模拟预测(文))已知i是虚数单位,若2i3iz−=+,则2iz=()A.1i−+B.1i
+C.1i−−D.1i−【答案】A【解析】由()()()()2i3i2i62i3i111i3i3i3i1022zz−−−−−−====−++−,所以1122zi=+,因此112i2i(i)=i122z
=+−,故选:A2.(2022·宁夏吴忠·模拟预测(理))若复数z满足()31i3iz+=+(i为虚数单位),则z=()A.12i+B.12i−C.2i+D.2i−【答案】A【解析】因为复数z满足()31i3iz+=+(i为虚数单位),所以()()33i1i3i3i24i12i1i1i22z
+++++=====++−,故选:A.3.(2022·天津五十七中模拟预测)已知i是虚数单位,则202220211()1++=−iii___________.【答案】2【解析】因为2021()=ii,()()()22022220222022202221
11211112====+++−−+=−iii+iiiiii,所以202220211()11121++=−+=+=−iiii,故答案为:2.