Question

設復數z=+(1-i)²,則(1+z)⁷展開式的第五項是

A.-2i                B.-21i             C.35                D.-35i

Answer 1

C

解析:∵z=+(1-i)²=-i,∴(1+z)⁷=(1-i)⁷,其展開式的第五項為T₅=(-i)⁴==35.故選C.