Answer :

To find the domain of a function with a root, you set it ≥ 0
So, the equation will look like this:
8 - 8x ≥ 0
-8x ≥ 8
-8x ÷ 8 ≤ 8 ÷ -8
x ≤ 1
Therefore, the domain is
(-∞, 1]
[tex]8-8x\geq0\\ 8x\leq8\\ x\leq1\\ x\in(-\infty,1][/tex]