For which value of $\mathrm{<mn>9</mn>}$ will the system of inequalities $\left\{\begin{array}{l}{\mathrm{x}}^2-\mathrm{<mn>7</mn>}\mathrm{x}+\mathrm{<mn>21</mn>}\ge 0\\ \mathrm{x}>0\end{array}\right.$  have a solution?