1.a^2(b-c)+b^2(c-a)+c^2(a-b)
=ab(a-b)-c(a^2-b^2)+c^2(a-b)-c(a+b)(a-b)
=(a-b)[ab-c(a+b)+c^2]
=(a-b)(ab-ac-bc+c^2)
=(a-b)[a(b-c)-c(b-c)]
=(a-b)(b-c)(a-c)
1.a^2(b-c)+b^2(c-a)+c^2(a-b)
=ab(a-b)-c(a^2-b^2)+c^2(a-b)-c(a+b)(a-b)
=(a-b)[ab-c(a+b)+c^2]
=(a-b)(ab-ac-bc+c^2)
=(a-b)[a(b-c)-c(b-c)]
=(a-b)(b-c)(a-c)