Answer:
[tex]x^{2}-16x+64[/tex]
Step-by-step explanation:
To solve this problem you must apply the proccedure shown below:
1. You have the following perfect square trinomial given in the problem:
[tex]x^{2}-16+[/tex]
2. To fill the missing term, you must divide the coefficient -16 by 2 and then you must square it, as following:
[tex](\frac{-16}{2})^{2}=(-8)^{2}=64[/tex]