What should be added to 9p² + 14p so that the sum is a perfect square?

Question: What should be added to 9p² + 14p so that the sum is a perfect square?

Solution:
(3p)² + 2.3p.(7/3) + (7/3)²
= (3p + 7/3)²

so, (7/3)² or, 49/9 should be added to make it a perfect square.