Câu hỏi 2

\(\begin{array}{l}{V_{\left( {I;3} \right)}}\left( {AB} \right) = A'B' \Rightarrow A'B' = 3AB\\{V_{\left( {I;3} \right)}}\left( {AC} \right) = A'C' \Rightarrow A'C' = 3AC\\{V_{\left( {I;3} \right)}}\left( {BC} \right) = B'C' \Rightarrow B'C' = 3BC\\ \Rightarrow \dfrac{{{P_{A'B'C'}}}}{{{P_{ABC}}}} = \dfrac{{3\left( {AB + AC + BC} \right)}}{{AB + AC + BC}} = 3\end{array}\)

Chọn C.