Can you pls help i need to submit it soon ..i'll mark you brainlist

Answer:
9x² + 72x + 144 OR x² + 8x + 16
Step-by-step explanation:
Data :
Sqaure has a side let say p = 3x + 12
As the formula for square area is
Area = A = p² or length × width
As square has all equal side
So ( 3x + 12 ) ( 3x + 12 )
⇒ 9x² + 36x +36x + 144
9x² + 72x + 144
OR take 9 common
x² + 8x + 16