1.2x^3-x^2-2x+1=2x(x^2-1)-(x^2-1)=(x-1)(x+1)(2x-1)2.x^2-9y^2-2x+6y=x^2-2x+1-9y^2+6y-1=(x-1)^2-(3y-1)^2=(x+3y-2)(x-3y)3.x^3-y^3+x^2y-xy^2 =x^2(x+y)-y^2(x+y)=(x-y)(x+y)^2