Question

(x-2y+3 cube)+(x+2y-3 cube) expand

Answer 1

(x-2y+3^3) x (x-2y - 3^3)

take x-2y as a, and 3^3 as b. Use algebraic identity (a-b)(a+b)

(x-2y)^2 - 81^2

x^2 - 4xy + 4y^2 - 6561

Hope it helps!!

Answer 2

Given problem is $(x-2y+3^3)+(x+2y-3^3)$

Expand exponent first

$=(x-2y+27)+(x+2y-27)$

remove parenthesis

$=x-2y+27+x+2y-27$

combine like terms

$=2x$

Hence final answer is 2x.