Answer:
(2x - 3y)(2x + 3y)
Step-by-step explanation:
Assuming you require the expression factorised.
4x² - 9y² ← is a difference of squares and factors in general as
a² - b² = (a - b)(a + b)
4x² - 9y²
= (2x)² - (3y)²
= (2x - 3y)(2x + 3y)