(ii) z2 + 6z – 8 = 0
Sol. z2 + 6z – 8 = 0
∴ z2 + 6z = 8 .... (i)
Third term = ( ½ × coefficient of z)2
= ( ½ × 6)2
= (3)2
= 9
Adding 9 to both sides of (i), we get,
z2 + 6z + 9 = 8 + 9
∴ (z + 3)2 = 17
∴ z + 3 = ±√17
∴ z = - 3 ± √17
∴ z = –3 + √17 or z = –3 – √17
