((a-i)/(1+i))^2=[(a-i)(1-i)/(1+i)(1-i) )] ^2 分母有理化
=[-4a-2(a^2-1)i]/4 i^2=-1
=-a-[(a^2-1)/2]i
而((a-i)/(1+i))^2=-2+bi
则有:-a = -2 对应系数相等,还有常数项相等
-[(a^2-1)/2] = b
解得:a=2
b=-3/2
((a-i)/(1+i))^2=[(a-i)(1-i)/(1+i)(1-i) )] ^2 分母有理化
=[-4a-2(a^2-1)i]/4 i^2=-1
=-a-[(a^2-1)/2]i
而((a-i)/(1+i))^2=-2+bi
则有:-a = -2 对应系数相等,还有常数项相等
-[(a^2-1)/2] = b
解得:a=2
b=-3/2