z(1-2i)=1+i(i为虚数单位),复数z=A.3+i/3 B.-1+3i/3 C.-1+3i/5 D.3+i/5
问题描述:
z(1-2i)=1+i(i为虚数单位),复数z=
A.3+i/3 B.-1+3i/3 C.-1+3i/5 D.3+i/5
答
z=a+bi (a+bi)*(1-2i)=1+i
a+bi-2ai+2b=1+i
a+2b=1 b-2a=1
5b=3 b=3/5
a=-1/5
z= -1/5+3/5i =(-1+3i)/5
选C.答案少了()