(i) x2 + 8x + 9 = 0
Sol. x2 + 8x + 9 = 0
∴ x2 + 8x = –9 .....(i)
Third term = ( ½ × coefficient of x)2
= ( ½ × 8)2
= (4)2
= 16
Adding 16 to both sides of (i) we get,
x2 + 8x + 16 = –9 + 16
∴ (x + 4)2 = 7
∴ (x + 4) = ±√7
∴ x = – 4 ±√7
∴ x = – 4 +√7 or x = – 4 – √7
