课堂练习:1、计算 (1)(2+4i)+(3-4i)= (2)(-3-4i)+(2+i)+(1-5i)= (3)已知Z1=a+bi,Z2=c+di,若Z1+Z2是纯虚数,则有( ) A.a-c=0且b-d≠0 B. a-c=0且b+d≠0 C. a+c=0且b-d≠0 D.a+c=0且b+d≠0
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