What is the square of (2a + 3b) multiplied by the square of (2a-3b)

What is the square of (2a + 3b) multiplied by the square of (2a-3b)

The square of (2a + 3b) multiplied by the square of (2a-3b)
=(2a + 3b) (2a-3b)]
=(Party 4a-9b)
=16a4-72a-b + 81b4