Answer:
The middle term would be 48x
Explanation:
In order to find this, we need to take the squares of the end terms and put them in a perfect square. Then we can distribute to find the middle term.
(3x + 8)^2
(3x + 8)(3x + 8)
9x^2 + 24x + 24x + 64
9x^2 + 48x + 64