Consider the following question.
(1+i)4+(1−i)4=
Using Formula,
a4+b4=((a2+b2)2−2a2b2)
(1+i)4+(1−i)4=((1+i)2+(1−i)2−2(1−i2))
=(1+i2+2i+1+i2−2i−2+2i2)
=−2
Hence, this is the required answer.