Find the product:

(2x – y)(2x + y)(4x² + y²)

First solving (2x – y) (2x+y)

Using the identity (a +b) (a–b) = a² – b²

Here a = 2x and b = y

= (2x)² – y²

= 4x² – y²

Now solving (4x² – y² ) (4x² + y²)

Again using the identity (a +b) (a–b) = a² – b²

Here a = 4x² and b = y²

= (4x²)² – (y²)²

= 16 x⁴ – y⁴