1. 2x(a-b)(a+b)-(b-a)(b^2+ab+a^2)=(a-b)[(2x(a+b)+(b^2+ab+a^2)]2. x^4+2x^2+1-4x^2=x^4-2x^2+1=(x^2-1)^2=(x-1)^2 * (x+1)^2
