1
(4-7i)³=64-336i-588+343i=-524+7i
2
z²=i |z|=1
z=cosπ/2+isinπ/2
zk=cos[(π/2+2πk)/2]+isin[(π/2+2πk)/2]
k=0 z=cosπ/4+isinπ/4=√2/2+√2/2*i
k=1 z=cos5π/4+isin5π/4=-√2/2-√2/2*i
3
zk=cos[(π/2+2πk)/3]+isin[(π/2+2πk)/3]
k=0 z=cosπ/6+isinπ/6=√3/2+1/2*i
k=1 z=cos5π/6+isin5π/6=-√3/2+1/2*i
k=2 z=cos3π/2+isin3π/2=-i