ω=e2πi/3,ω3=1
1+ω+ω2=0
Find the number of distinct z with
z+1 ω ω²
ω z+ω² 1
ω² 1 z+ω = 0
1. Write M=zI+A
2. Study A using 1+ω+ω2=0, ω3=1
3. Reduce det(zI+A) and count distinct z
M = zI + A, A = 1 ω ω²
ω ω² 1
ω² 1 ω
Row sums =1+ω+ω2=0⇒detA=0
trA=1+ω2+ω=0
A2=0
det(zI+A)=z3+(trA)z2+c2z+detA
trA=detA=0,c2=0⇒det(zI+A)=z3
z3=0⇒z=0 (multiplicity 3)
Answer: 1