证明：
-1+i=√2*e^(3iπ/4)
（-1+i）^7
=[√2*e^(3iπ/4)]^7
=(√2)^7*e^(3iπ/4*7)
=8√2*e^(21iπ/4)
=8√2*e^(5iπ/4+2*2iπ)
=8√2*e^(5iπ/4)
=8[√2*e^(5iπ/4)]
=-8（1+i）
证毕