The limit \(\lim_{n \to \infty} \sum_{i=1}^{n} \sqrt{9 + \frac{6i}{n}} \cdot \frac{6}{n}\) is the limit of a Riemann sum with \(n\) subintervals of equal width and sample points equal to right endpoints for the definite integral \(\int_{9}^{15} \text{____} \sum dx\)
