计算 分式的加减法.

题目

计算 分式的加减法.
b/(a+b)-a/a-b
(a-b/ab)+(b-c/bc)+(c-a/ca)
(1/x-1)-(1/x+1)-(2/x^2+1)
(4/a+2)+a-2

答案

b/(a+b)-a/(a-b)=[b(a-b)-a(a+b)]/(a²-b²)=(-b²-a²)/(a²-b²)=(b²+a²)/(b²-a²)(a-b/ab)+(b-c/bc)+(c-a/ca) =(1/b)-(1/a)+(1/c)-(1/b)+(1/a)-(1/c)=0(1/x-1)-(1/x+...