化简:(a-c)/(a-b)(b-c)+(b-c)/(a-b)(a-c)+(a-b)/(c-a)(b-c)
參考答案:(a-c)/(a-b)(b-c)+(b-c)/(a-b)(a-c)+(a-b)/(c-a)(b-c)
=[(a-c)^2+(b-c)^2-(a-b)^2]/[(a-b)(b-c)(a-c)]
=(a^2-2ac+c^2+b^2-2bc+c^2-a^2+2ab-b^2)/[(a-b)(b-c)(a-c)]
=(2c^2-2ac-2bc+2ab)/[(a-b)(b-c)(a-c)]
=2(c-b)(c-a)/[(a-b)(b-c)(a-c)]
=2/(a-b)