分解因式：1.9（a-b)^2-16(a+b)^2 2.3x^3-12x^2y+12xy^2 3.25(x-y)^2+10(y-x)+1

1 9（a-b)^2-16(a+b)^2=-7a^2-50ab-7b^2=-(7a+b)(a+7b)2 3x^3-12x^2y+12xy^2=3x(x^2-4xy+4y^2)=3x(x-2y)^23 25(x-y)^2+10(y-x)+1=25(x-y)^2-10(x-y)+1=[5(x-y)-1]^2=(5x-5y-1)^2