Giúp e câu 2,3 với ạ

Câu 2:

Ta có: 

\(\begin{array}{l}
\dfrac{{{F_{{A_1}}}}}{{{F_{{A_2}}}}} = \dfrac{{{d_0}{V_1}}}{{{d_0}{V_2}}} = \dfrac{{{V_1}}}{{{V_2}}} = \dfrac{{\dfrac{m}{{{D_1}}}}}{{\dfrac{m}{{{D_2}}}}} = \dfrac{{{D_2}}}{{{D_1}}} = \dfrac{{27000}}{{78000}} = \dfrac{9}{{26}}\\
 \Rightarrow {F_{{A_2}}} = \dfrac{{26}}{9}{F_{{A_1}}}
\end{array}\)

Câu 3: 

Ta có:

\(\begin{array}{l}
\dfrac{{{F_{{A_1}}}}}{{{F_{{A_2}}}}} = \dfrac{{{d_1}V}}{{{d_2}V}} = \dfrac{{{d_1}}}{{{d_2}}} = \dfrac{{8000}}{{10000}} = 0,8\\
 \Rightarrow {F_{{A_2}}} = 1,25{F_{{A_1}}}
\end{array}\)