f(x)为偶函数f(-x)=f(x)g(x)为奇函数g(-x)=-g(x)A f(x)+g(x)=1/(x-1)B f(-x)+g(-x)=f(x)-g(x)=-1/(x+1)A+B得 2f(x)=1/(x-1) -1/(x+1) = (x+1-(x-1))/(x^2-1)= 2/(x^2-1)f(x)=1/(x^2-1)A-B得 2g(x)=1/(x-1)+1/(x+1)=(x+1+x-1)/(x^2-1)=2x/(x^2-1) g(x)=x/(x^2-1)