1、原式
=n[(m²-2m)²+2(m²-2m)+1]
=n[m²-2m+1]²
=n(m-1)^4
2、(x²+y²-1)²-4x²y²
=(x²+y²-1)²-(2xy)²
=(x²+y²-1+2xy)(x²+y²-1-2xy)
=[(x+y)²-1][(x-y)²-1]
=(x+y+1)(x+y-1)(x-y+1)(x-y-1)
3、a(2a-b)+2a(b-2a)²+2a(b-2a)²-a(b-2a)²
=a(2a-b)+3a(2a-b)²
=a(2a-b)[1+3(2a-b)]
=a(2a-b)(6a-3b+1)