To express the product \( 2x \cdot 2x \cdot 2x \cdot 2x \) in exponent form, you can count the number of times \( 2x \) is multiplied together. Since \( 2x \) is multiplied by itself 4 times, you can write this as:
\[ (2x)^4 \]
So, \( 2x \cdot 2x \cdot 2x \cdot 2x = (2x)^4 \).