(3p - 7)(3p + 7) has the form of (a-b)(a+b).
So (a-b)(a+b)= a^2-b^2.
So in (3p - 7)(3p + 7), a=3p and b=7.
So (3p - 7)(3p + 7) = 3p^2 + 7^2 = 9p^2-49.
So (3p-7)(3p+7)= 9p^2 - 49.
You can check your answer (very important):
We'll use p=1.
(3-7)(3+7) = -40
9-49 = -40
The answer has been approved.
Hope this Helps! :)
