Question

Упростите выражение
(1+xy)^2-(1-xy)^2

Answer 1

= ( 1 + 2XY + X^2Y^2) - ( 1 - 2XY + X^2Y^2) = 
= 1 + 2XY + X^2Y^2 - 1 + 2XY - X^2Y^2 =
= 4XY