a/(ab+a+1)=a/(ab+a+1)b(/bc+b+1)=ab/(abc+ab+a)=ab/(ab+a+1) （上下同时乘以a）c/(ac+c+1)=bc/(abc+bc+b)=bc/(bc+b+1)=1/(ab+a+1) （上下同时乘以ba）∴a/(ab+a+1)+b/(bc+b+1)+c/(ac+c+1)=(a+ab+1)/(ab+a+1)=1...通分，大哥！已知:abc=1,将下列分式进行通分a/ab+a+1,b/bc+b+1,c/ac+c+1通分，分母一样了，叫做通分，通好了a/(ab+a+1)；b(/bc+b+1)=ab/(ab+a+1) ；c/(ac+c+1)=1/(ab+a+1)然后相加为1