When the quadratic function $\bm{f}$ is graphed in the $xy$-plane, where $\bm{y}=\bm{f}(\bm{x})$, its vertex is $(-3,6)$. One of the $x$-intercepts of this graph is $\left(-\frac{17}{4},0\right)$. What is the other $x$-intercept of the graph?