abc=1所以b=1/acab=1/cbc=1/a所以原式=a/(1/c+a+1)+(1/ac)/(1/a+1/ac+1)+c/(ac+c+1)第一个式子上下同乘c第二个式子上下同乘ac所以=ac/(ac+c+1)+1/(ac+c+1)+c/(ac+c+1)=(ac+c+1)/(ac+c+1)=1
