If z = 2 – i√7 , prove that 3z3 – 4z2 + z + 88 = 0
=> z = 2 – i√7
=> z – 2 = –i√7
=> (z – 2)2 = (–i√7)2
=> z2 – 4z + 4 = –7
=> z2 – 4z + 11 = 0.
3z3 – 4z2 + z + 88 = 3z(z2 – 4z + 11) + 8(z2 – 4z + 11)
= 3z(0) + 8(0)
= 0
