5真题再现1.(2019•新课标Ⅲ)若z(1+i)=2i,则z=()A.﹣1﹣iB.﹣1+iC.1﹣iD.1+i【答案】D【解析】由z(1+i)=2i,得z==1+i.故选:D.2.(2019•新课标Ⅰ)设z=,则|z|=()A.2B.C.D.1【答案】C【解析】由z=,得|z|=||=.故选:C.3.(2018•新课标Ⅰ)设z=+2i,则|z|=()A.0B.C.1D.【答案】C【解析】z=+2i=+2i=﹣i+2i=i,则|z|=1.故选:C.4.(2018•新课标Ⅲ)(1+i)(2﹣i)=()A.﹣3﹣iB.﹣3+iC.3﹣iD.3+i【答案】D【解析】(1+i)(2﹣i)=3+i.故选:D.5.(2018•新课标Ⅱ)i(2+3i)=()A.3﹣2iB.3+2iC.﹣3﹣2iD.﹣3+2i【答案】D【解析】i(2+3i)=2i+3i2=﹣3+2i.故选:D.6.(2018•新课标Ⅱ)=()A.iB.C.D.【答案】D【解析】==+.故选:D.7.(2017•全国)=()A.B.C.D.【答案】D【解析】=.故选:D.8.(2017•新课标Ⅰ)下列各式的运算结果为纯虚数的是()A.i(1+i)2B.i2(1﹣i)C.(1+i)2D.i(1+i)【答案】C【解析】A.i(1+i)2=i•2i=﹣2,是实数.B.i2(1﹣i)=﹣1+i,不是纯虚数.C.(1+i)2=2i为纯虚数.D.i(1+i)=i﹣1不是纯虚数.故选:C.9.(2017•新课标Ⅲ)设复数z满足(1+i)z=2i,则|z|=()A.B.C.D.2【答案】C【解析】 (1+i)z=2i,∴(1﹣i)(1+i)z=2i(1﹣i),z=i+1.则|z|=.故选:C.10.(2017•新课标Ⅱ)(1+i)(2+i)=()A.1﹣iB.1+3iC.3+iD.3+3i【答案】B【解析】原式=2﹣1+3i=1+3