\(\left\{{}\begin{matrix}A=-3x^5y^3z^2\\B=2x^5.y^3.z^3\end{matrix}\right.\) x;y;z khác 0
\(\dfrac{A}{B}=-\dfrac{3}{2}.\dfrac{x^5}{x^5}.\dfrac{y^3}{y^3}.\dfrac{z^2}{z^3}=-\dfrac{3}{2z}\) A;B trái dấu => \(\dfrac{A}{B}< 0\Leftrightarrow\dfrac{3}{2z}>0\Rightarrow Z>0\)