Giải thích các bước giải:
$a+b+c=abc\rightarrow\dfrac{1}{ab}+\dfrac{1}{bc}+\dfrac{1}{ca}=1$
Mà
$\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}=2$
$\rightarrow (\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c})^2=4$
$\rightarrow \dfrac{1}{a^2}+\dfrac{1}{b^2}+\dfrac{1}{c^2}+2(\dfrac{1}{ab}+\dfrac{1}{bc}+\dfrac{1}{ca})=4$
$\rightarrow \dfrac{1}{a^2}+\dfrac{1}{b^2}+\dfrac{1}{c^2}+2.1=4$
$\rightarrow \dfrac{1}{a^2}+\dfrac{1}{b^2}+\dfrac{1}{c^2}=2$
