x^6-x^5 4ab-2b 12s^2t-20st^2 2a^4-6a^3-2a^2 1/2m^3+2mn^3 3a(x-y)-6b(y-x) -4a^2b-6ab^2+8ab
问题描述：
x^6-x^5 4ab-2b 12s^2t-20st^2 2a^4-6a^3-2a^2 1/2m^3+2mn^3 3a(x-y)-6b(y-x) -4a^2b-6ab^2+8ab
5(m+n)^2-4m-4n 求分解因式
答
x^6-x^5=x^5(x-1)
4ab-2b =2b(2a-1)
12s^2t-20st^2 =4st(3s-5t)
2a^4-6a^3-2a^2 =2a^2(a^2-3a-1)
1/2m^3+2mn^3=1/2m(m^2+4n^3)
3a(x-y)-6b(y-x) =3a(x-y)+6b(x-y)=3(x-y)(a+2b)
-4a^2b-6ab^2+8ab=-2ab(2a+3b-4)
5(m+n)^2-4m-4n =5(m+n)^2-4(m+n)=(m+n)(5m+5n-4)