$(6 x)^{2}$ simplified expression

Step 1 ：The question is asking for the simplified expression of \((6x)^{2}\).

Step 2 ：This can be simplified by applying the power of a product rule in mathematics, which states that the power of a product is the product of each factor raised to the power.

Step 3 ：In this case, we can apply the rule to get \(6^{2} * x^{2}\).

Step 4 ：So, the simplified expression of \((6x)^{2}\) is \(\boxed{36x^{2}}\).