Simplify (4/ab)²: Complete the Squared Fraction Expression

To solve the problem, let's apply exponent rules to the given expression:

• Step 1: Identify the fraction's components. The numerator is $4$ and the denominator is $a \times b$.
• Step 2: Apply the exponent rule for fractions, $\left(\frac{m}{n}\right)^p = \frac{m^p}{n^p}$. In this case, $m = 4$, $n = a \times b$, and $p = 2$.

Now, we apply the exponent:

$\left(\frac{4}{a \times b}\right)^2 = \frac{4^2}{(a \times b)^2}$.

This results in:

$\frac{16}{a^2 \times b^2}$.

However, the expression $\frac{4^2}{(a \times b)^2}$ matches choice 2 from the provided options, hence:

The correct answer to the problem in its intended form is $\frac{4^2}{\left(a\times b\right)^2}$.