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已知abc=1,求证:a/(ab+a+1)+b/(bc+a+1)+c/(ca+c+1)=1

题目详情
已知abc=1,求证:a/(ab+a+1)+b/(bc+a+1)+c/(ca+c+1)=1
▼优质解答
答案和解析
因为abc=1,所以:
a/(ab+a+1)+b/(bc+b+1)+c/(ca+c+1)
=a/(ab+a+abc)+b/(bc+b+abc)+c/(ca+c+1)
=a/[a(b+1+bc)]+b/[b(c+1+ac)]+c/(ca+c+1)
=1/(b+1+bc)+1/(c+1+ac)+c/(ca+c+1)
=abc/(b+abc+bc)+1/(ac+c+1)+c/(ca+c+1)
=abc/[b(1+ac+c)]+1/(ac+c+1)+c/(ca+c+1)
=ac/(1+ac+c)+1/(ac+c+1)+c/(ca+c+1)
=(ac+1+c)/(1+c+ac)=1