答:Z=50+(100+j200)//(-j400)
=50+(100+j200)(-j400)÷(100+j200-j400)
=50+(80000-j40000))÷(100-j200)
=50+89443∠-26.6(度)÷224∠-63.4(度)
=50+399∠36.8(度)
=50+319+j239
=369+j239
答:Z=50+(100+j200)//(-j400)
=50+(100+j200)(-j400)÷(100+j200-j400)
=50+(80000-j40000))÷(100-j200)
=50+89443∠-26.6(度)÷224∠-63.4(度)
=50+399∠36.8(度)
=50+319+j239
=369+j239