(1)
(x+5)²(x-5)²-(2x+1)²(2x-1)²
=(x²-25)² -(4x²-1)²
=(5x²-26) (-3x²-24)
=-3(5x²-26) (x²+8)
=-3(5x^4 +14x² -208)
=-15x^4 -42x² +624
(2)
A=2x²-x+1 ,A-2B=x-1
2B=A-(x-1)=2x²-x+1 -x +1=2x²-2x+2
B=x²-x+1
(3)
4a(1-b)²+2(b-1)²
=4a(b-1)² +2(b-1)²
=2(2a+1)(b-1)²