Question

(2x-1)²-(2x+1)•(2x-1)=

Answer 1

4x^2 - 4x + 1 - (4x^2 - 1) =
= 4x^2 - 4x + 1 - 4x^2 + 1 = 
= - 4x + 2 = 
= - 2(2x - 1) 

Answer 2

$(2x - 1)^2 - (2x+1)(2x-1) = 4x^2 -4x + 1 - 4x^2 +1 = \\ =-4x +2 = -2(2x-1)$