If Z= (13−5i)(4−9i) find z6
Rationalize the complex number by multiplying and dividing by 4+9i
13−5i4−9i × 4+9i4+9i = 52−20i+117i−45i216−i281
=97+97i97= (1+i)
In polar form
z=√2 (cosπ4+isinπ4)
z6 = [√2(cosπ4+isinπ4)]6
(√2)6[(cosπ4+isinπ4)]6
z6= 8[cos 3π2 + isin3π2]
=8[0-i] = -8i