The expression $\left(3 x^{4}\right)^{2}$ can be written in the form $3^{a} x^{b}$ where: - $a=$ Preview - $b=$ Preview

Step 1 ：The given expression is \(\left(3 x^{4}\right)^{2}\).

Step 2 ：We can simplify this expression by applying the power of a power rule in exponents, which states that \((a^{m})^{n} = a^{mn}\). Here, \(a\) is \(3x^{4}\) and \(n\) is \(2\).

Step 3 ：So, we can rewrite the expression as \(3^{2} x^{4*2}\).

Step 4 ：Final Answer: \(a=\boxed{2}\)

Step 5 ：Final Answer: \(b=\boxed{8}\)