1.原式=x^4-2x^2+1-x^2
=(x^2-1)^2-x^2
=(x^2+x-1)(x^2-x-1)
2.原式=x^2(1-y)+x(y-1)+y(1-y)
=x^2(1-y)-x(1-y)+y(1-y)
=(x^2-x+y)(1-y)
3.原式=a(x-2y)+b(2y-x)+c(x-2y)
=a(x-2y)-b(x-2y)+c(x-2y)
=(a-b+c)(x-2y)
4.原式=(a^2)^2+2(a^2)(4b)^2+(4b^2)^2
=(a^2+4b^2)^2
=(a^2+(2b)^2)^2
5.原式=x^2+2*x(3y)+(3y)^2-2x-6y+1
=(x+3y)^2-2*(x+3y)*1+1^2
=(x+3y-1)^2
6.原式=ab(a^2-b^2)+a^2+2ab+b^2+1-2ab
=ab(a+b)(a-b)+(a+b)^2-2ab
=ab(a-b)(a+b)(1+a+b)-2ab
=ab((a+b+1)(a+b)(a-b)-2)
备注：我学编程的,只用小括号