(4x+2y) whole cube minus (4x-2y) whole cube

Answer 1

(4x+2y)-(4x-2y)

For subtraction of polynomials, you have to distribute the -1 (Doesn't need to be shown, but adding it is helps) to clear the parenthesis

(4x+2y)-1(4x-2y)

Distribute that -1

4x+2y-4x+2y

Combine like terms. (The 4x-4x=0)

2y+2y = 4y

Answer 2

(4x + 2y)³ - (4x - 2y)³

Using the Binomial Theorem, we get:

(4x)³ + 3(4x)²(2y) + 3(4x)(2y)² + (2y)³ - [(4x)³ - 3(4x)²(2y) + 3(4x)(2y)² - (2y)³]

= 192x²y + 16y³

^