Đáp án:
Tần số
\[\begin{array}{l}
f = \frac{1}{{2\pi }}\sqrt {\frac{k}{m}} ;f' = \frac{1}{{2\pi }}\sqrt {\frac{{k'}}{{m'}}} \\
\frac{{f'}}{f} = \frac{{\frac{1}{{2\pi }}\sqrt {\frac{{k'}}{{m'}}} }}{{\frac{1}{{2\pi }}\sqrt {\frac{k}{m}} }} = \sqrt {\frac{{k'}}{{m'}}} .\sqrt {\frac{m}{k}} = \sqrt {\frac{{k'}}{k}} .\sqrt {\frac{m}{{m'}}}
\end{array}\]