1.恒等式的证明定理若a,b,c是实数,且任意两个不互为相反数,则有恒等式(a-b)/(a+b)+(b-c)/(b+c)+(c-a)/(c+a)=-(a-b)(b-c)(c-a)/(a+b)(b+c)(c+a)①证明(a-b)/(a+b)+(b-c)/(b+c)+(c-a)/(c+a)=(a-b)/(a+b)+(-(a-b)-(c-a))/(b+c)+(c-a)/(c+a) 1. Proof Theorem of Identity If a, b, c are real numbers, and any two are not opposite to each other, then there is an identity of (ab) / (a ​​+ b) + (bc) / (b + c) + (a + b) + (b + c) (c + a) = - (ab) (bc) (ca) / (a ​​+ b) b + c + ca / ​​c + a = ab / a + b + - - ab - ca / ​​b + c + ca / ​​c + a)