Câu trả lời:

 lại cộng 5 vậy

 

cho \(\dfrac{1}{a}\)+\(\dfrac{1}{b}\)+\(\dfrac{1}{c}\)=2 (1)  ;  \(\dfrac{1}{a^2}\)+\(\dfrac{1}{b^2}\)+\(\dfrac{1}{c^2}\)=2 (2)
c/m a+b+c= abc