\[при\ m = 1\frac{1}{2};n = - \frac{1}{3}:\ \]
\[m^{2}n^{4} = \left( 1\frac{1}{2} \right)^{2} \cdot \left( - \frac{1}{3} \right)^{4} =\]
\[= \left( \frac{3}{2} \right)^{2} \cdot \left( \frac{1}{3} \right)^{4} = \frac{9 \cdot 1}{4 \cdot 81} =\]
\[= \frac{1 \cdot 1}{4 \cdot 9} = \frac{1}{36}\text{.\ \ }\]