(1)-3a²b+6ab (2)(x²-2x)²+2（x²-2x）+1 (3)(m+n)(m-n)-(1-2n)

(1)-3a²b+6ab (2)(x²-2x)²+2（x²-2x）+1 (3)(m+n)(m-n)-(1-2n)
(1)-3a²b+6ab (2)(x²-2x)²+2（x²-2x）+1 (3)(m+n)(m-n)-(1-2n)

(1)-3a²b+6ab (2)(x²-2x)²+2（x²-2x）+1 (3)(m+n)(m-n)-(1-2n)
(1)-3a²b+6ab
=3ab（2-a）
(2)(x²-2x)²+2（x²-2x）+1
= (x²-2x+1)²
(3)(m+n)(m-n)-(1-2n)
=m²-n²-1+2n
=m²-(n²-2n+1)
=m²-(n-1)²
=(m+n-1)(m-n+1)
有不明白的可以追问!
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