设abc=1,求(a\ab+a+1)+(b\bc+b+1)+(c\ac+c+1)求大神帮助

1/ab+a+1 + 1/bc+b+1 + 1/ac+c+1 =abc/(ab+a+abc)+ 1/(bc+b+1) + 1/(ac+c+1) =bc/(bc+b+1)+ 1/(bc+b+1) + 1/(ac+c+1) =(bc+1)/(bc+b+1)+ 1/(ac+c+1) =(bc+1)/(bc+b+abc)+ 1/(ac+c+1) =(bc+1)/[b(c+1+ac)]+ b/[b(ac+c+1)] =(bc+1+b)/[b(c+1+ac)] =(bc+abc+b)/(bc+b+abc) =1