1.原式=[(2(x+y)+(x-y)][2(x+y)-(x-y)]
=(2x+2y+x-y)(2x+2y-x+y)
=(3x+y)(x+3y)
2.原式=x^n-1(x^2-3x+2)
=x^n-1*(x-1)(x-2)
3.原式=2*(m^4-2m+1)
=2*(m^2-1)^2
=2*[(m+1)(m-1)]^2
=2*(m+1)^2(m-1)^2