初2数学题．急．在线等

1 .(x-y)(x-3y)+y*y
=x^2-3xy-xy+3y^2+y^2
=x^2-4xy+4y^2
=(x-2y)^2

2.x*x*x*x*x(x-2y)+x*x(2y-x)
=x^2(x-2y)(x^3-1)
=x^2(x-2y)(x-1)(x^2+x+1)

(x-y)(x-3y)+y*y =x*x-4xy+3y*y+y*y
=x*x-4xy+4y*y
=(x-2y)的平方.......
这个上标怎么来？

1、展开得到x^2-4xy+4y^2=（x-2y）^2
2、原式=x*x*(x-2y)(x^3-1)=x^2*(x-2y)(x-1)(x^2+x+1)

(x-2y)^2