)n(1−1−2i) =(i−1)n(−2i) If n=1,(i−1)(−2i)=−2i2+2i=2+2i If n=2,−2i(i−1)2=−2i(−2i)=−4 If n=4,−2i(i−1)4=−2i(−2i)(−2i)=8i If n=6,−2i(i−1)6=−2i(−2i)(−2i)(−2i)=16 So, least value of n for which given complex is positive is 6.