1..(x-y)^2-(x+y)(x-y) 2..-2(a-1)^3+12(a-1)^3+18(1-a)求你了

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1..(x-y)^2-(x+y)(x-y) 2..-2(a-1)^3+12(a-1)^3+18(1-a)求你了
1..(x-y)^2-(x+y)(x-y) 2..-2(a-1)^3+12(a-1)^3+18(1-a)求你了

1..(x-y)^2-(x+y)(x-y) 2..-2(a-1)^3+12(a-1)^3+18(1-a)求你了
1..(x-y)^2-(x+y)(x-y)
=(x-y)[(x-y)-(x+y)]
=-2y(x-y)
2..-2(a-1)^3+12(a-1)^2+18(1-a)
=-2(a-1)^3+12(a-1)^2-18(a-1)
=-2(a-1)[(a-1)^2-6(a-1)+9]
=-2(a-1)(a-1-3)^2
=-2(a-1)(a-4)^2