（-2x+1)(-2x-1)-(2x-1)^2.(2x-1)(x+2)-(x-2)^2-(x+2)^2.(a-2b)^2

（-2x+1)(-2x-1)-(2x-1)^2.
=(2x-1)(2x+1)-(2x-1)²
=(2x-1)(2x+1-2x+1)
=2(2x-1)
=4x-2
(2x-1)(x+2)-(x-2)^2-(x+2)^2.
=(2x²+3x-2)-(x²-4x+4)-(x²+4x+4)
=2x²+3x-2-x²+4x-4-x²-4x-4
=3x-10
(a-2b)^2-(2b+a)(2b-a)
=(a-2b)²+(a+2b)(a-2b)
=(a-2b)(a-2b+a+2b)
=2a(a-2b)
=2a²-4a