p² + 6p – 16

Coefficient of p² = 1

Therefore, we have

p² + 6p + 3² – 3² – 16 (Adding and subtracting 3²)

= (p + 3)² – 5² (Completing the square)

= (p + 3 + 5) (p + 3 – 5)

= (p + 8) (p – 2)