Use the properties of logarithms to expand $\log \left(y x^{8}\right)$.

Step 1 ：Use the properties of logarithms to expand \(\log \left(y x^{8}\right)\).

Step 2 ：The properties of logarithms state that \(\log(ab) = \log(a) + \log(b)\) and \(\log(a^n) = n\log(a)\). We can use these properties to expand the given expression.

Step 3 ：Applying these properties, we get \(\log \left(y x^{8}\right) = \log(y) + \log(x^{8})\).

Step 4 ：Further simplifying, we get \(\log \left(y x^{8}\right) = \log(y) + 8\log(x)\).

Step 5 ：Final Answer: The expanded form of \(\log \left(y x^{8}\right)\) is \(\boxed{8\log(x) + \log(y)}\).