x^2-4xy+3y^2因式分解

1.x²-4xy+3y²,用十字相乘法
=(x-3y)(x-y)
2.(ax²y²-a)/(xy+1)
=a[(xy)²-1]/(xy+1)
=a(xy+1)(xy-1)/(xy+1),约掉公因数xy+1
=a(xy-1)
3.[(a-2b)²-4(a-2b)+4]/(a-2b-2)
=[(a-2b)-2]²/(a-2b-2),约掉其中一个公因数a-2b-2
=a-2b-2
4.m^4-2(m²-1/2)
=m^4-2m²+1
=(m²-1)²
=(m+1)²(m-1)²

原式=x^2-(4y+1)x+3y^2-y-2(a^2+b^2-c^2-2ab)/(a-b-c)
=[(a-b)^2-c^2]/(a-b-c)
=(a-b+c)(a-b-c)/(a-b-c)
=a-b+c
(x^2-6x)^2+18(x^2-6x)+81=0
[(x^2-6x)+9]^2=0
(x^2-6x+9)^2=0
x^2-6x+9...