急哒！！！一道初二分式

abc=1
b=1/ac
ab=1/c
bc=1/a

(ab+b+1)/(ab+a+1)乘以（ac+c+1)/（bc+c+1)
=(ab+b+1)(ac+c+1)/[(ab+a+1)(bc+c+1)]
=(1/c+1/ac+1)(ac+c+1)/[(1/c+a+1)(1/a+c+1)]
上下同乘ac,其中分母中第一个括号乘c，第二个乘a
=(a+1+ac)(ac+c+1)/[(1+ac+c)(1+ac+a)]
=1

***（ac+b+1)/(ab+a+1)是否应是（ac+a+1)/(ab+a+1)？？ ***
（ac+a+1)/(ab+a+1)*（ac+c+1)/（bc+c+1)
=1/b*bc(ac+a+1)/c(ab+a+1)*（ac+c+1)/（bc+c+1)
=1/b*(abc^2+abc+bc)/(abc+ac+c)*（ac+c+1)/（bc+c+1)
=1/b*(bc+c+1)/(ac+c+1)*（ac+c+1)/（bc+c+1)
=1/b