b/(bc+b+1)+a/(ab+a+1)+c/(ac+c+1)=abc/(abc*c+abc+ac)+ac/(abc+ac+c)+c/(ac+c+1)——第一个式子分子分母都乘以ac,第二个式子分子分母都乘以c=1/(ac+c+1)+ac/(ac+c+1)+c/(ac+c+1)——abc=1代入得到=(1+ac+c)/(ac+c+1...