通分1/(a-b)(a-c),1/(b-c)(b-a),1/(c-a)(c-b)

问题描述:

通分1/(a-b)(a-c),1/(b-c)(b-a),1/(c-a)(c-b)

1/(a-b)(a-c)=(b-c)/(a-b)(a-c)(b-c)
1/(b-c)(b-a)=-(a-c)/(a-b)(a-c)(b-c)
1/(c-a)(c-b)=-(a-b)/(a-b)(a-c)(b-c)