关于X的方程X^2+(M+2i)X+2+2i=0（m属于R)有实根n
n^2+(M+2i)n+2+2i=0
n^2+Mn+2+(2n+2)i=0
n^2+Mn+2=0,2n+2=0
n=-1,m=3
复数z=3-i