Ta có :
\(\dfrac{1}{3^{400}}=\dfrac{1}{\left(3^4\right)^{100}}=\dfrac{1}{81^{100}}\)
\(\dfrac{1}{4^{300}}=\dfrac{1}{\left(4^3\right)^{100}}=\dfrac{1}{64^{100}}\)
Vì \(81^{100}>64^{100}\)
\(\Rightarrow\dfrac{1}{81^{100}}< \dfrac{1}{61^{100}}\)
Vậy ...
